JP2023158197A - Light-emitting device, electronic apparatus, and illumination device - Google Patents

Abstract

To provide a light-emitting device with high luminous efficiency and high reliability.SOLUTION: A light-emitting device includes a host material and a guest material in a light-emitting layer. The host material has a function of converting triplet excited energy into light emission. The guest material emits fluorescence. The molecular structure of the guest material includes a luminophore and a protecting group. Five protecting groups are included in one molecule of the guest material. By introducing the protecting group into the molecule, the triplet excited energy transfer from the host material to the guest material by a dexter mechanism is suppressed. As the protecting group, an alkyl group or a branched-chain alkyl group is used. By using a material with a five-membered ring skeleton as the host material, the light-emitting device with higher luminous efficiency can be obtained.SELECTED DRAWING: Figure 1

Description

One embodiment of the present invention relates to a light-emitting device, or a display device, an electronic device, and a lighting device including the light-emitting device.

Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to a product, a method, or a manufacturing method. Alternatively, one aspect of the present invention relates to a process, machine, manufacture, or composition of matter. Therefore, more specifically, the technical fields of one embodiment of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, Or, their manufacturing method can be mentioned as an example.

In recent years, research and development of light-emitting devices using electroluminescence (EL) has been actively conducted. The basic structure of these light emitting devices is such that a layer containing a luminescent substance (EL layer) is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this device, light emission from the luminescent substance can be obtained.

Since the above-mentioned light-emitting device is self-luminous, a display device using it has advantages such as excellent visibility, no need for a backlight, and low power consumption. Furthermore, it has advantages such as being able to be made thin and lightweight and having a high response speed.

In the case of a light-emitting device (e.g., an organic EL device) in which an organic compound is used as a luminescent substance and an EL layer containing the luminescent organic compound is provided between a pair of electrodes, a voltage may be applied between the pair of electrodes. As a result, electrons are injected from the cathode and holes are injected from the anode into the luminescent EL layer, causing current to flow. Then, the injected electrons and holes recombine to bring the luminescent organic compound into an excited state, and light emission can be obtained from the excited luminescent organic compound.

The types of excited states formed by organic compounds include the singlet excited state (S ^* ) and the triplet excited state (T ^* ).Emission from the singlet excited state is fluorescent, and emission from the triplet excited state is called fluorescence. It is called phosphorescence. Moreover, their statistical production ratio in a light emitting device is S ^* :T ^* =1:3. Therefore, a light-emitting device using a compound that emits phosphorescence (phosphorescent material) can achieve higher luminous efficiency than a light-emitting device using a compound that emits fluorescence (fluorescent material). Therefore, development of light-emitting devices using phosphorescent materials capable of converting triplet excited state energy into light emission has been actively conducted in recent years.

Among light-emitting devices using phosphorescent materials, light-emitting devices that emit blue light in particular have not yet been put into practical use because it is difficult to develop stable compounds with a high triplet excitation energy level. Therefore, development of light-emitting devices using more stable fluorescent materials is underway, and methods for increasing the luminous efficiency of light-emitting devices using fluorescent materials (fluorescent light-emitting devices) are being searched for.

In addition to phosphorescent materials, thermally activated delayed fluorescence (TADF) materials are known as materials that can convert part or all of the energy of a triplet excited state into light emission. . In a thermally activated delayed fluorescent material, a singlet excited state is generated from a triplet excited state by reverse intersystem crossing, and the singlet excited state is converted into light emission.

In order to increase luminous efficiency in a light-emitting device using a thermally activated delayed fluorescent material, it is necessary to not only efficiently generate a singlet excited state from a triplet excited state in the thermally activated delayed fluorescent material, but also to It is important that luminescence can be efficiently obtained from the excited state, that is, that the fluorescence quantum yield is high. However, it is difficult to design a light-emitting material that satisfies these two requirements at the same time.

In addition, in a light emitting device having a thermally activated delayed fluorescent material and a fluorescent material, the singlet excitation energy of the thermally activated delayed fluorescent material is transferred to the fluorescent material to cause emission from the fluorescent material. A method for obtaining this has been proposed (see Patent Document 1). That is, a light emitting device using a thermally activated delayed fluorescent material as a host material and a fluorescent material as a guest material has been proposed.

Japanese Patent Application Publication No. 2014-45179

To improve the efficiency of a fluorescent light-emitting device, for example, in a light-emitting layer containing a host material and a guest material, the triplet excitation energy of the host material is converted into singlet excitation energy, and then the singlet excitation is applied to the fluorescent material, which is the guest material. One example is a method of increasing the luminous efficiency of a fluorescent light emitting device by transferring energy. However, the process of converting the triplet excitation energy of the host material into singlet excitation energy competes with the process of deactivating the triplet excitation energy. Therefore, the triplet excitation energy of the host material may not be sufficiently converted to singlet excitation energy. For example, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, the path by which triplet excitation energy is deactivated is the lowest triplet excitation energy level ( _T1 level) possessed by the fluorescent material. A deactivation path is considered in which the triplet excitation energy of the host material is transferred. Energy transfer through this deactivation pathway does not contribute to light emission, leading to a decrease in the light emission efficiency of the fluorescent light emitting device. This deactivation path can be suppressed by reducing the concentration of the guest material, but at the same time, the rate of energy transfer from the host material to the guest material in the singlet excited state also slows down. This makes it susceptible to quenching by deteriorating substances and impurities. Therefore, the brightness of the light emitting device tends to decrease, leading to a decrease in reliability.

Therefore, in one embodiment of the present invention, in a host material and a guest material of a light-emitting layer included in a light-emitting device, triplet excitation energy of the host material is suppressed from moving to the T1 level of the guest material, and triplet excitation energy of the host material is suppressed from moving to the _T1 level of the guest material. The purpose of this method is to efficiently convert atomic excitation energy into singlet excitation energy of a guest material, thereby increasing the fluorescence emission efficiency of a light-emitting device and further improving its reliability.

Another object of one embodiment of the present invention is to provide a light-emitting device with high luminous efficiency. Another object of one embodiment of the present invention is to provide a highly reliable light-emitting device. Another object of one embodiment of the present invention is to provide a light-emitting device with reduced power consumption. Another object of one embodiment of the present invention is to provide a novel light-emitting device. Another object of one embodiment of the present invention is to provide a novel light-emitting device. Another object of one embodiment of the present invention is to provide a novel display device.

Note that the description of the above issues does not preclude the existence of other issues. Note that one embodiment of the present invention does not necessarily need to solve all of these problems. Problems other than the above are naturally obvious from the description, etc., and it is possible to extract problems other than the above from the description, etc.

In one embodiment of the present invention, in order to suppress triplet excitation energy of a host material from moving to the _T1 level of a guest material in a light-emitting layer included in a light-emitting device, a host material (energy donor) and a guest material ( Provided is a light emitting device that can mainly suppress energy transfer due to the Dexter mechanism among energy transfer between the energy acceptor and the energy acceptor.

In order to suppress the energy transfer due to the Dexter mechanism, it is preferable that the distance between the energy donor and the energy acceptor in the light emitting layer is set to such a distance that the energy transfer does not occur. Therefore, in one aspect of the present invention, in order to separate the distance between the energy donor and the luminophore possessed by the energy acceptor to a distance that does not cause the energy transfer, an energy donor having a bulky structure and an energy donor having a protective group are used. A light emitting device using an acceptor is provided. Further, in one embodiment of the present invention, the triplet level (T1 level) of the energy donor is preferably higher than the singlet level (S1 level) of the energy acceptor.

Note that in one embodiment of the present invention, a material having a substituent on a five-membered ring skeleton is used as an energy donor having a bulky structure. Further, although a fluorescent material is used as an energy acceptor, the fluorescent material has a bulky structure because it has a protective group. The five-membered ring skeleton possessed by the energy donor is particularly preferably an imidazole skeleton or a triazole skeleton.

Therefore, one embodiment of the present invention is a light-emitting device having a light-emitting layer between a pair of electrodes, the light-emitting layer having a first material and a second material, the first material having triplet excitation. The second material can convert energy into luminescence and has a five-membered ring skeleton, the second material can convert singlet excitation energy into luminescence, and has a luminophore and five or more protecting groups, and the luminophore is fused It is an aromatic ring or a condensed heteroaromatic ring, and the five or more protecting groups are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and 3 or more carbon atoms. The light-emitting device has any one of the above 12 or less trialkylsilyl groups, and the T1 level of the first material is higher than the S1 level of the second material.

In the above structure, at least four of the five or more protecting groups are each independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms; It is preferable that it is any one of the above and 10 or less trialkylsilyl groups.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. the second material is capable of converting singlet excitation energy into luminescence and has a five-membered ring skeleton; the second material is capable of converting singlet excitation energy into luminescence; and has a luminophore and at least four protecting groups; A fused aromatic ring or a fused heteroaromatic ring, the four protecting groups are not directly bonded to the fused aromatic ring or the fused heteroaromatic ring, and the four protecting groups are each independently an alkyl group having 3 to 10 carbon atoms, It has either a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms, and the T1 level of the first material is the same as the second material. This is a light emitting device that has a higher level than the S1 level.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. The second material can convert singlet excitation energy into luminescence and has a five-membered ring skeleton, and the second material can convert singlet excitation energy into luminescence and has a luminophore and two or more diarylamino groups, and the second material has a luminophore and two or more diarylamino groups. is a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring is bonded to two or more diarylamino groups, and the aryl groups in the two or more diarylamino groups each independently bond to at least one Each protecting group is independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. The device is a light emitting device in which the T1 level of the first material is higher than the S1 level of the second material.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. The second material can convert singlet excitation energy into luminescence and has a five-membered ring skeleton, and the second material can convert singlet excitation energy into luminescence and has a luminophore and two or more diarylamino groups, and the second material has a luminophore and two or more diarylamino groups. is a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring is bonded to two or more diarylamino groups, and the aryl groups in the two or more diarylamino groups each independently bond to at least two Each protecting group is independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. The device is a light emitting device in which the T1 level of the first material is higher than the S1 level of the second material.

Moreover, in the above structure, it is preferable that the diarylamino group is a diphenylamino group.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. The second material is capable of converting singlet excitation energy into luminescence and has a five-membered ring skeleton, and the second material is capable of converting singlet excitation energy into luminescence and has a luminophore and a plurality of protecting groups. However, each protecting group is independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms. the luminophore is a fused aromatic ring or fused heteroaromatic ring, and at least one of the atoms constituting the protecting group is located directly on one side of the fused aromatic ring or fused heteroaromatic ring, and At least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the fused ring or fused heteroaromatic ring, and the T1 level of the first material is higher than the S1 level of the second material. It is also an expensive light emitting device.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. The second material can convert singlet excitation energy into luminescence, has a five-membered ring skeleton, and has a luminophore and two or more diphenylamino groups, and has a luminophore. is a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups are each independently at the 3-position and It has a protecting group at the 5-position, and the protecting group is each independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 12 carbon atoms. It is a light emitting device that has any one of trialkylsilyl groups, and the T1 level of the first material is higher than the S1 level of the second material.

In the above structure, the 5-membered ring skeleton preferably has any one of a pyrazole skeleton, an imidazole skeleton, and a triazole skeleton, and the nitrogen atom that does not participate in the double bond of the imidazole skeleton and the triazole skeleton is substituted or unsubstituted. It is more preferable to have an aromatic hydrocarbon group having 6 to 13 carbon atoms.

Another embodiment of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, the light emitting layer having a first material and a second material, the first material having a triple layer. The second material can convert singlet excitation energy into luminescence and has a five-membered ring skeleton, and the second material can convert singlet excitation energy into luminescence and has a luminophore and two or more protecting groups. is a fused aromatic ring or a fused heteroaromatic ring, and the two or more protecting groups are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, The first material has a 5-membered ring skeleton, and the 5-membered ring skeleton has at least either an imidazole skeleton or a triazole skeleton. , the nitrogen atom that does not participate in the double bond of the imidazole skeleton and the triazole skeleton has a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms, and the T1 level of the first material is the second This is a light-emitting device that has a higher S1 level than that of the material.

Moreover, in the above structure, the aromatic hydrocarbon group is preferably a phenyl group.

Moreover, in the above structure, it is preferable that the alkyl group is a branched alkyl group.

Moreover, in the above structure, it is preferable that the branched alkyl group has a quaternary carbon.

Further, in the above configuration, it is preferable that the fused aromatic ring or fused heteroaromatic ring contains any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, pyrene, tetracene, perylene, coumarin, quinacridone, and naphthobisbenzofuran.

Moreover, in the above structure, it is preferable that the light-emitting layer further includes a third material, and the first material and the third material form an exciplex.

In the above configuration, it is preferable that the emission spectrum of the exciplex overlaps with the absorption band on the longest wavelength side of the second material.

In the above structure, the five-membered ring skeleton preferably has any one of a pyrazole skeleton, an imidazole skeleton, and a triazole skeleton.

Further, in the above configuration, it is preferable that the first material is a metal complex. Further, it is more preferable that the metal complex has a metal of Group 8 to 10 and period 5 and 6, and the 5-membered ring skeleton is coordinated to the metal.

Further, in the above configuration, it is preferable that the first material exhibits phosphorescence.

Further, in the above configuration, it is preferable that the emission spectrum of the first material overlaps with the absorption band on the longest wavelength side of the second material.

Further, in the above structure, the concentration of the second material in the light emitting layer is preferably 2 wt% or more and 30 wt% or less.

Another embodiment of the present invention is a light-emitting device having a light-emitting layer between a pair of electrodes, the light-emitting layer having an energy donor and an energy acceptor, and the energy acceptor emitting triplet excitons. The energy acceptor has a five-membered ring skeleton, the energy acceptor has a luminophore and five or more protecting groups, and the luminophore is a fused aromatic ring or a fused heteroaromatic ring. 5 or more protecting groups are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. The T1 level of the energy donor is higher than the S1 level of the energy acceptor, and the triplet excitation energy of the energy donor is converted to the singlet excitation energy of the energy acceptor. This is a light-emitting device that produces light emitted from an acceptor.

In the above configuration, the light emission derived from the energy acceptor is preferably fluorescent light emission.

Another embodiment of the present invention is a display device including a light-emitting device having each of the above structures and at least one of a color filter and a transistor. Another embodiment of the present invention is an electronic device including the display device and at least one of a housing and a touch sensor. Another aspect of the present invention is a lighting device including a light emitting device having each of the above configurations and at least one of a housing and a touch sensor. Further, one embodiment of the present invention includes not only a light-emitting device including a light-emitting device but also an electronic device including a light-emitting device. Therefore, a light emitting device in this specification refers to an image display device or a light source (including a lighting device). In addition, a display module in which a connector such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) is attached to a light emitting device, a display module in which a printed wiring board is provided at the end of the TCP, or a COG (Chip On The light emitting device may also include a display module in which an IC (integrated circuit) is directly mounted using the glass method.

According to one embodiment of the present invention, a light-emitting device with high luminous efficiency can be provided. Alternatively, in one embodiment of the present invention, a highly reliable light-emitting device can be provided. Alternatively, in one embodiment of the present invention, a light-emitting device with reduced power consumption can be provided. Alternatively, in one embodiment of the present invention, a novel light-emitting device can be provided. Alternatively, in one embodiment of the present invention, a novel light-emitting device can be provided. Alternatively, in one embodiment of the present invention, a novel display device can be provided. Alternatively, novel organic compounds can be provided.

Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily need to have all of these effects. Note that effects other than these are obvious from the description, drawings, claims, etc., and effects other than these can be extracted from the description, drawings, claims, etc.

1A and 1B are schematic cross-sectional views of a light-emitting layer of a light-emitting device according to one embodiment of the present invention. FIG. 1C is a diagram illustrating the correlation of energy levels of a light-emitting device according to one embodiment of the present invention. FIG. 2A is a conceptual diagram of a conventional guest material. FIG. 2B is a conceptual diagram of a guest material used in a light-emitting device according to one embodiment of the present invention. FIG. 3A is a structural formula of a guest material used in a light-emitting device according to one embodiment of the present invention. FIG. 3B is a ball-and-stick diagram of a guest material used in a light-emitting device according to one embodiment of the present invention. FIG. 4A is a schematic cross-sectional view of a light-emitting layer of a light-emitting device according to one embodiment of the present invention. FIGS. 4B and 4C are diagrams illustrating the correlation of energy levels of a light-emitting device according to one embodiment of the present invention. FIG. 5A is a schematic cross-sectional view of a light-emitting layer of a light-emitting device according to one embodiment of the present invention. FIGS. 5B and 5C are diagrams illustrating a correlation between energy levels of a light-emitting layer of a light-emitting device according to one embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of a light-emitting device according to one embodiment of the present invention. FIG. 7A is a top view illustrating a display device according to one embodiment of the present invention. FIG. 7B is a schematic cross-sectional view illustrating a display device according to one embodiment of the present invention. 8A and 8B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. 9A and 9B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. 10A to 10D are perspective views illustrating a display module according to one embodiment of the present invention. 11A to 11C are diagrams illustrating an electronic device according to one embodiment of the present invention. 12A and 12B are perspective views illustrating a display device according to one embodiment of the present invention. FIG. 13 is a diagram illustrating a lighting device according to one embodiment of the present invention. FIG. 14 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 15 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 16 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 17 is a diagram illustrating the electroluminescence spectrum of the light emitting device according to the example. FIG. 18 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 19 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 20 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 21 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 22 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 23 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 24 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 25 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 26 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 27 is a diagram illustrating the electroluminescence spectrum of the light emitting device according to the example. FIG. 28 is a diagram illustrating external quantum efficiency-luminance characteristics of a comparative light-emitting device according to an example. FIG. 29 is a diagram illustrating an electroluminescence spectrum of a comparative light emitting device according to an example. FIG. 30 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 31 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 32 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 33 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 34 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 35 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 36 is a diagram illustrating the relationship between the emission spectrum and the absorption spectrum according to the example. FIG. 37 is a diagram illustrating the relationship between external quantum efficiency and guest material concentration according to the example. FIG. 38 is a diagram illustrating the results of a reliability test according to the example. FIG. 39 is a diagram illustrating the results of a reliability test according to the example. FIG. 40 is a diagram illustrating the results of a reliability test according to the example. FIG. 41 is a diagram illustrating the results of a reliability test according to the example. FIG. 42 is a diagram illustrating the results of a reliability test according to the example. FIG. 43 is a diagram illustrating the results of a reliability test according to the example. FIG. 44 is a diagram illustrating the results of a reliability test according to the example. FIGS. 45A and 45B are diagrams illustrating NMR charts of compounds according to reference examples. FIG. 46 is a diagram illustrating an NMR chart of a compound according to a reference example. FIG. 47 is a diagram illustrating an NMR chart of a compound according to a reference example. FIG. 48 is a diagram illustrating an NMR chart of a compound according to a reference example. FIG. 49 is a diagram illustrating the results of light emission lifetime measurement of a light emitting device according to an example. FIG. 50 is a diagram illustrating the results of light emission lifetime measurement of a light emitting device according to an example. FIG. 51 is a diagram illustrating the results of light emission lifetime measurement of a light emitting device according to an example. FIG. 52 is a diagram illustrating external quantum efficiency-luminance characteristics of a light emitting device according to an example. FIG. 53 is a diagram illustrating an electroluminescence spectrum of a light emitting device according to an example. FIG. 54 is a diagram illustrating the results of a reliability test according to the example. FIG. 55 is a diagram illustrating the results of light emission lifetime measurement of a light emitting device according to an example. FIGS. 56A and 56B are diagrams illustrating NMR charts of compounds according to reference examples. FIG. 57 is a diagram illustrating an NMR chart of a compound according to a reference example.

Hereinafter, embodiments of the present invention will be described in detail using the drawings. However, the present invention is not limited to the following description, and the form and details thereof may be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the contents described in the embodiments and examples shown below.

Note that the position, size, range, etc. of each structure shown in the drawings etc. may not represent the actual position, size, range, etc. for ease of understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings or the like.

Further, in this specification and the like, ordinal numbers such as first, second, etc. are used for convenience and may not indicate the order of steps or the order of lamination. Therefore, for example, the description can be made by replacing "first" with "second" or "third" as appropriate. Furthermore, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify one aspect of the present invention.

Furthermore, in this specification and the like, when explaining the structure of the invention using drawings, the same reference numerals may be used in common between different drawings.

Furthermore, in this specification and the like, the terms "film" and "layer" can be used interchangeably. For example, the term "conductive layer" may be changed to the term "conductive film." Alternatively, for example, the term "insulating film" may be changed to the term "insulating layer."

Furthermore, in this specification and the like, a singlet excited state (S ^* ) refers to a singlet state that has excitation energy. Further, the S1 level is the lowest singlet excitation energy level, and refers to the lowest singlet excitation state (S1 state) excitation energy level. Further, a triplet excited state (T ^* ) is a triplet state having excitation energy. Further, the T1 level is the lowest triplet excitation energy level, and is the lowest excitation energy level of the triplet excited state (T1 state). Note that in this specification and the like, even when simply described as a singlet excited state and a singlet excited energy level, the S1 state and S1 level may be represented. Moreover, even when described as a triplet excited state and a triplet excited energy level, it may also represent a T1 state and a T1 level.

Furthermore, in this specification and the like, a fluorescent material is a compound that emits light in the visible light region when relaxing from a singlet excited state to a ground state. A phosphorescent material is a compound that emits light in the visible light region at room temperature when relaxing from a triplet excited state to a ground state. In other words, a phosphorescent material is one of the compounds that can convert triplet excitation energy into visible light.

Furthermore, in this specification and the like, the blue wavelength region is 400 nm or more and less than 490 nm, and blue light emission has at least one emission spectrum peak in this wavelength region. Further, the green wavelength range is 490 nm or more and less than 580 nm, and the green light emission has at least one emission spectrum peak in this wavelength range. Further, the red wavelength range is from 580 nm to 680 nm, and the red light emission has at least one emission spectrum peak in this wavelength range.

(Embodiment 1)
In this embodiment, a light-emitting device that is one embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

<Example of configuration of light emitting device>
First, the structure of a light-emitting device according to one embodiment of the present invention will be described below with reference to FIGS. 1A to 1C.

FIG. 1A is a schematic cross-sectional view of a light-emitting device 150 according to one embodiment of the present invention.

The light emitting device 150 has a pair of electrodes (electrode 101 and electrode 102), and has an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light emitting layer 130.

In addition to the light-emitting layer 130, the EL layer 100 shown in FIG. 1A includes functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119.

Note that, in this embodiment, of the pair of electrodes, the electrode 101 is described as an anode and the electrode 102 is a cathode, but the configuration of the light emitting device 150 is not limited thereto. That is, the electrode 101 may be used as a cathode, the electrode 102 may be used as an anode, and the layers between the electrodes may be stacked in the reverse order. That is, the hole injection layer 111, the hole transport layer 112, the light emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked in the order from the anode side.

Note that the configuration of the EL layer 100 is not limited to the configuration shown in FIG. It is sufficient to adopt a configuration having the following. Alternatively, the EL layer 100 reduces the hole or electron injection barrier, improves the hole or electron transportability, inhibits the hole or electron transportability, or suppresses the quenching phenomenon caused by the electrode. It is also possible to have a structure including a functional layer having functions such as the ability to perform the following functions. Note that each functional layer may be a single layer or may have a structure in which a plurality of layers are laminated.

<Light-emitting mechanism of light-emitting device>
Next, the light emitting mechanism of the light emitting layer 130 will be explained below.

In the light emitting device 150 of one embodiment of the present invention, by applying a voltage between the pair of electrodes (electrode 101 and electrode 102), electrons are transferred from the cathode and holes from the anode to the EL layer 100. is injected and current flows. Among the excitons generated by recombination of carriers (electrons and holes), the ratio of singlet excitons to triplet excitons (hereinafter referred to as exciton generation probability) is 1:3 due to statistical probability. In other words, the ratio of singlet excitons produced is 25%, and the ratio of triplet excitons produced is 75%, so contributing triplet excitons to light emission improves the luminous efficiency of the light emitting device. It is important to make this happen. Therefore, it is preferable to use a material having a function of converting triplet excitation energy into light emission for the light-emitting layer 130.

Examples of materials having the function of converting triplet excitation energy into light emission include compounds that can emit phosphorescence (hereinafter also referred to as phosphorescent materials). In this specification and the like, a phosphorescent material refers to a compound that exhibits phosphorescence and does not exhibit fluorescence in a temperature range from a low temperature (for example, 77 K) that can be obtained with liquid nitrogen to room temperature or less. The phosphorescent material preferably contains a metal element with large spin-orbit interaction, specifically transition metal elements, particularly platinum group elements (groups 8 to 10 and elements in the 5th and 6th period (ruthenium)). (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)), and in particular, by having iridium, the singlet ground state and triplet This is preferable because the transition probability related to direct transition to and from the excited state can be increased.

Moreover, a TADF material is mentioned as a material having a function of converting triplet excitation energy into light emission. Note that the TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting energy from triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be up-converted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy (for example, at room temperature), and a singlet excited state can be efficiently generated. In addition, in exciplexes (also called exciplexes, exciplexes, or exciplexes) in which two types of substances form an excited state, the difference between the S1 level and the T1 level is extremely small, and the triplet excitation energy is compared to the singlet excitation energy. It functions as a TADF material that can be converted into

Note that a phosphorescence spectrum observed at a low temperature (for example, 10 K) may be used as an index of the T1 level. For TADF materials, draw a tangent at the short wavelength side of the fluorescence spectrum, set the energy of the wavelength of the extrapolated line to the S1 level, draw a tangent at the short wavelength side of the phosphorescence spectrum, and set the extrapolated line to the S1 level. It is preferable that the difference between S1 and T1 is 0.2 eV or less when the energy of the wavelength of is taken as the T1 level.

FIG. 1B is a schematic cross-sectional view showing a light-emitting layer 130 of a light-emitting device that is one embodiment of the present invention. In one embodiment of the invention, the light-emitting layer 130 includes a compound 131, a compound 132, and a compound 133. Compound 133 has a function of converting triplet excitation energy into luminescence and has a five-membered ring skeleton. Compound 132 has a function of converting singlet excitation energy into luminescence and has a protecting group. Since fluorescent materials have high stability, it is preferable to use a fluorescent material as the compound 132 in order to obtain a highly reliable light emitting device. Compound 131 is a host material, and carrier recombination preferably occurs on compound 131. In the light-emitting device of one embodiment of the present invention, both singlet excitation energy and triplet excitation energy of excitons generated by recombination of carriers in compound 131 pass through compound 133, and finally singlet excitation energy of compound 132. Preferably, the compound 132 emits light due to energy transfer to the state. Here, in the light emitting layer 130, the compound 133 is an energy donor, and the compound 132 is an energy acceptor. In FIG. 1B, the light emitting layer 130 is a fluorescent light emitting layer using a compound 131 as a host material and a compound 132 as a guest material. Compound 133 also functions as an energy donor. Further, the light emitting layer 130 can obtain light emission derived from the compound 132 which is a guest material.

<Configuration example 1 of light emitting layer>
FIG. 1C is an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 of one embodiment of the present invention. The light emitting layer 130 shown in FIG. 1B includes a compound 131, a compound 132, and a compound 133. In one aspect of the invention, compound 132 is a fluorescent material with a protecting group. Further, compound 133 has a function of converting triplet excitation energy into luminescence. In this configuration example, a case where the compound 133 is a phosphorescent material will be described.

Further, the correlation between the energy levels of the compound 131 and the compound 132 in the light emitting layer 130 is shown in FIG. 1C. Note that the notations and symbols in FIG. 1C are as follows.
・Comp (131): Compound 131
・Comp (133): Compound 133
・Guest (132): Compound 132
・_SC1 : S1 level of compound 131・_TC1 : T1 level of compound 131・_TC3 : T1 level of compound 133・_TG : T1 level of compound 132・_SG : S1 level of compound 132

In the light-emitting device of one embodiment of the present invention, carrier recombination mainly occurs in the compound 131 included in the light-emitting layer 130, thereby generating singlet excitons and triplet excitons. Here, since compound 133 is a phosphorescent material, by selecting a material with the relationship T _C3 ≦ T _C1 , both the singlet and triplet excitation energies generated in compound 131 are transferred to the T _C3 level of compound 133. (Fig. 1C route A ₁ ). Note that some carriers can be recombined with compound 133.

Note that the phosphorescent material used in the above configuration preferably contains heavy atoms such as Ir, Pt, Os, Ru, and Pd. As described above, in this configuration example, the phosphorescent material acts as an energy donor, so the quantum yield may be high or low. When a phosphorescent material is used as compound 133 (energy donor), energy transfer from the triplet excitation energy level of the energy donor to the singlet excitation energy level of the guest material (energy acceptor) is preferable because it is an allowable transition. . Therefore, the triplet excitation energy of compound 133 can be transferred to the S1 level (S _G ) of compound 132, which is the guest material, by the process of route _A2 . In route _A2 , compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. In this case, it is preferable that T _C3 ≧ _SG because the excitation energy of compound 133 is efficiently transferred to the singlet excited state of compound 132, which is the guest material. Specifically, a tangent line is drawn at the tail of the short wavelength side of the phosphorescence spectrum of compound 133, and the energy of the wavelength of the extrapolated line is taken as T _C3 , and the wavelength of the absorption edge of the absorption spectrum of compound 132 or the short wavelength of the emission spectrum is When a tangent line is drawn at the side hem and the energy of the wavelength of the extrapolated line is _SG , it is preferable that T _C3 ≧ _SG .

Here, in the light-emitting layer 130, the compound 131, the compound 132, and the compound 133 are mixed. Therefore, a process (route A ₃ in FIG. 1C) in which the triplet excitation energy of compound 133 is converted into the triplet excitation energy of compound 132 may occur competing with the routes A ₁ and A ₂ described above. Since compound 132 is a fluorescent material, the triplet excitation energy of compound 132 does not contribute to light emission. That is, when the energy transfer of route _A3 occurs, the luminous efficiency of the light emitting device decreases. In reality, the energy transfer process _A3 from T _C3 to T _G is not direct, but involves a path where energy is transferred once to a triplet excited state higher than T _G in compound 132, and then becomes T _G by internal conversion. Although this is possible, the process is omitted in the diagram. The undesirable thermal deactivation process, ie, the energy transfer process to _TG , described hereinafter is all the same.

Here, fluorescence resonance energy transfer (FRET) or Förster mechanism (dipole-dipole interaction) and Dexter mechanism (electron exchange interaction) are known as energy transfer mechanisms between molecules. It is being Since the compound 132, which is an energy acceptor, is a fluorescent material, the Dexter mechanism is dominant in the energy transfer of route _A3 . Generally, the Dexter mechanism occurs significantly when the distance between compound 131, which is an energy donor, and compound 132, which is an energy acceptor, is 1 nm or less. Therefore, in order to suppress route _A3 , it is important to increase the distance between the host material and the guest material, that is, the distance between the energy donor and the energy acceptor.

In addition, the energy transfer from the singlet excitation energy level (S _C1 ) of compound 131 to the triplet excitation energy level (T _G ) of compound 132 is the transition from the singlet ground state to the triplet excited state of compound 132. Since direct transition is prohibited, it is unlikely to become the main energy transfer process, so it is not shown.

_TG in FIG. 1C is often an energy level derived from a luminophore in an energy acceptor. Therefore, in order to suppress route _A3 in more detail, it is important to increase the distance between the luminophores of the energy donor and the energy acceptor. A common method for increasing the distance between the luminophores of the energy donor and the energy acceptor is to lower the concentration of the energy acceptor in a mixed film of these compounds. However, when the concentration of the energy acceptor in the mixed film is reduced, not only the energy transfer from the energy donor to the energy acceptor based on the Dexter mechanism but also the energy transfer based on the Förster mechanism is suppressed. In that case, since route _A2 is based on the Förster mechanism, problems such as a decrease in luminous efficiency and a decrease in reliability of the light emitting device arise.

Therefore, the present inventors have found that the above-mentioned decrease in luminous efficiency can be suppressed by using a fluorescent material having a protecting group for increasing the distance from the energy donor as the energy acceptor. By having a protecting group, the fluorescent material can be made into a bulky energy acceptor.

<Concept of fluorescent materials with protecting groups>
FIG. 2A shows a conceptual diagram when a fluorescent material that does not have a protecting group, which is a general fluorescent material, is dispersed in a host material as a guest material, and FIG. A conceptual diagram is shown in which a fluorescent material having a protecting group is dispersed in a host material as a guest material. The host material may be read as an energy donor, and the guest material may be read as an energy acceptor. Here, the protecting group has the function of increasing the distance between the luminophore and the host material. In FIG. 2A, guest material 301 has a luminophore 310. Guest material 301 has a function as an energy acceptor. On the other hand, in FIG. 2B, guest material 302 has a luminophore 310 and a protecting group 320. Furthermore, in FIGS. 2A and 2B, guest material 301 and guest material 302 are surrounded by host material 330. In FIG. 2A, since the distance between the luminophore and the host material is close, the energy transfer from the host material 330 to the guest material 301 is due to the Förster mechanism (route B ₁ in FIGS. 2A and 2B) and the Dexter mechanism. Both movements (route B ₂ in FIGS. 2A and 2B) can occur. When triplet excitation energy is transferred from the host material to the guest material by the Dexter mechanism and a triplet excited state of the guest material is generated, if the guest material is a fluorescent material, the triplet excitation energy is non-radiatively deactivated. Therefore, this becomes a cause of a decrease in luminous efficiency.

On the other hand, in FIG. 2B, the guest material 302 has a protecting group 320. Therefore, the distance between the luminophore 310 and the host material 330 can be increased. Therefore, energy transfer (route B ₂ ) due to the Dexter mechanism can be suppressed.

Here, in order for the guest material 302 to emit light, since the Dexter mechanism is suppressed, the guest material 302 needs to receive energy from the host material 330 by the Förster mechanism. That is, it is preferable to efficiently utilize the energy transfer due to the Förster mechanism while suppressing the energy transfer due to the Dexter mechanism. It is known that energy transfer by the Förster mechanism is also affected by the distance between the host material and the guest material. Generally, when the distance between the host material 330 and the luminophore 310 of the guest material 302 is 1 nm or less, the Dexter mechanism becomes dominant, and when the distance is from 1 nm to 10 nm, the Förster mechanism becomes dominant. Generally, when the distance between the host material 330 and the luminophore 310 of the guest material 302 is 10 nm or more, energy transfer is difficult to occur.

Therefore, it is preferable that the protecting group 320 extends from the luminophore 310 within a range of 1 nm or more and 10 nm or less. More preferably, the thickness is 1 nm or more and 5 nm or less. With this configuration, it is possible to efficiently utilize the energy transfer due to the Förster mechanism while suppressing the energy transfer from the host material 330 to the guest material 302 due to the Dexter mechanism. Therefore, a light emitting device with high luminous efficiency can be manufactured.

Furthermore, in order to increase the energy transfer efficiency (improve the energy transfer speed) by the Förster mechanism, it is preferable to increase the concentration of the guest material 301 or the guest material 302 with respect to the host material 330. However, normally, as the concentration of the guest material increases, the energy transfer rate of the Dexter mechanism also increases, resulting in a decrease in luminous efficiency. Therefore, it has been difficult to increase the concentration of the guest material. In a fluorescent light emitting device using a material having the function of converting triplet excitation energy into light emission as a host material, a light emitting device in which the guest material concentration is as low as 1 wt % or less has been reported.

On the other hand, in a light-emitting device according to one embodiment of the present invention, a guest material having a protective group on a luminophore is used as a light-emitting layer. Therefore, the energy transfer due to the Förster mechanism can be efficiently utilized while suppressing the energy transfer due to the Dexter mechanism, so that the concentration of the guest material, which is an energy acceptor, can be increased. As a result, it is possible to suppress the energy transfer due to the Dexter mechanism while increasing the energy transfer rate due to the Förster mechanism, which are originally contradictory phenomena. The concentration of the guest material is preferably 2 wt% or more and 30 wt% or less, more preferably 5 wt% or more and 20 wt% or less, and still more preferably 5 wt% or more and 15 wt% or less, based on the host material. With this configuration, the speed of energy transfer by the Förster mechanism can be increased, so a light emitting device with high luminous efficiency can be obtained. Furthermore, by using a material having a function of converting triplet excitation energy into light emission as a host material, a fluorescent light emitting device having high light emitting efficiency equivalent to that of a phosphorescent light emitting device can be produced. Furthermore, since luminous efficiency can be improved by using a highly stable fluorescent material, a highly reliable light emitting device can be manufactured.

In particular, the effect of the light-emitting device of one embodiment of the present invention is not simply the effect of improving reliability due to the use of a highly stable fluorescent material. The energy transfer as described above always competes with the quenching process due to the effects of degradants and impurities. As the quenching rate constant of the quenching process increases over time, the rate at which the light emitting device emits light decreases. That is, the brightness of the light emitting device deteriorates. However, as described above, one embodiment of the present invention can increase the energy transfer rate due to the Förster mechanism compared to conventional light-emitting devices while suppressing the energy transfer due to the Dexter mechanism. can be made smaller and the life of the light emitting device can be extended.

Here, the term "luminophore" refers to an atomic group (skeleton) that causes luminescence in a fluorescent material. The luminophore generally has a π bond and preferably contains an aromatic ring, preferably a fused aromatic ring or a fused heteroaromatic ring. Moreover, as another aspect, a luminophore can be regarded as an atomic group (skeleton) containing an aromatic ring in which a transition dipole vector exists on a ring plane.

Examples of the fused aromatic ring or fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, and the like. In particular, fluorescent materials having a naphthalene skeleton, anthracene skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, or naphthobisbenzofuran skeleton are preferred because they have a high fluorescence quantum yield.

Further, the protecting group needs to have a triplet excitation energy level higher than the T1 level of the luminophore and the host material. Therefore, a saturated hydrocarbon group can be preferably used. This is because a substituent that does not have a π bond has a high triplet excitation energy level. Furthermore, a substituent that does not have a π bond does not have the function of transporting carriers (electrons or holes). Therefore, the saturated hydrocarbon group can increase the distance between the luminophore and the host material without substantially affecting the excited state or carrier transport properties of the host material. In addition, in organic compounds that simultaneously have a substituent that does not have a π bond and a substituent that has a π-conjugated system, a frontier orbital {HOMO (also known as Highest Occupied Molecular Orbital, highest occupied orbital) is present on the side of the substituent that has a π-conjugated system. ) and LUMO (Lowest Unoccupied Molecular Orbital, also referred to as the lowest unoccupied orbit)), and in particular, the luminophore often has a frontier orbit. As will be described later, the overlap of the HOMOs of both the energy donor and the energy acceptor and the overlap of the LUMOs of both are important for energy transfer by the Dexter mechanism. Therefore, by using a saturated hydrocarbon group as a protecting group, it is possible to increase the distance between the frontier orbital of the host material, which is an energy donor, and the frontier orbital of the guest material, which is an energy acceptor, thereby preventing energy transfer by the Dexter mechanism. Can be suppressed.

Specific examples of the protecting group include alkyl groups having 1 or more and 10 or less carbon atoms. Further, since it is necessary to keep the distance between the luminophore and the host material large, the protective group is preferably a bulky substituent. In other words, a substituent with large steric hindrance is preferable. Therefore, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms can be suitably used. In particular, the alkyl group is preferably a bulky branched alkyl group. Further, it is particularly preferable that the substituent has a quaternary carbon because it becomes a bulky substituent.

Further, it is preferable that one luminophore has five or more protecting groups. With this configuration, the entire luminophore can be covered with the protective group, so the distance between the host material and the luminophore can be adjusted appropriately. Further, although FIG. 2B shows a state in which a luminophore and a protecting group are directly bonded, it is more preferable that the protecting group is not directly bonded to a luminophore. For example, the protecting group may be bonded to the luminophore via a divalent or higher substituent such as an arylene group or an amino group. By bonding the protective group to the luminophore via the substituent, the distance between the luminophore and the host material can be effectively increased. Therefore, when a luminophore and a protecting group are not directly bonded, when one luminophore has four or more protecting groups, energy transfer by the Dexter mechanism can be effectively suppressed.

Further, the substituent having a valence of more than 2 which connects the luminophore to the protective group is preferably a substituent having a π-conjugated system. With this configuration, physical properties such as the emission color, HOMO level, and glass transition point of the guest material can be adjusted. Note that it is preferable that the protecting group be placed at the outermost position when looking at the molecular structure centering on the luminophore.

<Examples of fluorescent materials with protective groups and molecular structures>
Here, N,N'-[(2-tert-butylanthracene)-9,10- is a fluorescent material represented by the following structural formula (102) that can be used in a light-emitting device of one embodiment of the present invention. The structure of diyl]-N,N'-bis(3,5-di-tert-butylphenyl)amine (abbreviation: 2tBu-mmtBuDPhA2Anth) is shown. In 2tBu-mmtBuDPhA2Anth, the anthracene ring is the luminophore and the tertiary butyl (tBu) group acts as a protecting group.

A representation of the above 2tBu-mmtBuDPhA2Anth using a ball-and-stick model is shown in FIG. 3B. Note that FIG. 3B shows the state of 2tBu-mmtBuDPhA2Anth when viewed from the direction of the arrow in FIG. 3A (horizontal direction with respect to the anthracene ring surface). The shaded area in FIG. 3B represents the area directly above the anthracene ring surface, which is the luminophore, and it can be seen that there is a region directly above the area where the tBu group, which is the protective group, overlaps. For example, in FIG. 3B, the atom indicated by the arrow (a) is a carbon atom of the tBu group that overlaps with the shaded area, and the atom indicated by arrow (b) is the hydrogen atom of the tBu group that overlaps with the shaded area. be. That is, in 2tBu-mmtBuDPhA2Anth, an atom constituting a protecting group is located directly above one of the luminophore surfaces, and an atom constituting a protecting group is also located directly above the other surface. With this configuration, even when the guest material is dispersed in the host material, the distance between the anthracene ring and the host material can be increased in both the plane direction and the vertical direction of the anthracene ring, which is a luminophore, Energy transfer due to the Dexter mechanism can be suppressed.

In addition, in energy transfer by the Dexter mechanism, for example, when the transition related to energy transfer is a transition between HOMO and LUMO, the HOMOs of both the host material and the guest material overlap, and the LUMOs of both the host material and the guest material overlap. is important. When the HOMO and LUMO of both materials overlap, the Dexter mechanism occurs significantly. Therefore, in order to suppress the Dexter mechanism, it is important to suppress the overlap of the HOMO and LUMO of both materials. That is, it is important to keep the distance between the skeleton involved in the excited state and the host material large. Here, in fluorescent materials, luminophores often have both HOMO and LUMO. For example, if the HOMO and LUMO of the guest material extend above and below the plane of the luminophore (in 2tBu-mmtBuDPhA2Anth, above and below the anthracene ring), cover the upper and lower sides of the luminophore with protective groups. This is important in terms of molecular structure.

Further, in a fused aromatic ring or a fused heteroaromatic ring that functions as a luminophore, such as a pyrene ring or anthracene ring, a transition dipole vector exists on the ring plane. Therefore, in FIG. 3B, 2tBu-mmtBuDPhA2Anth preferably has a region where the tBu group, which is a protecting group, overlaps directly on the plane where the transition dipole vector exists, that is, on the plane of the anthracene ring. Specifically, at least one of the atoms constituting the plurality of protecting groups (tBu group in FIGS. 3A and 3B) is one of a fused aromatic ring or a fused heteroaromatic ring (anthracene ring in FIGS. 3A and 3B). and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the fused aromatic ring or fused heteroaromatic ring. With this configuration, even if the guest material is dispersed in the host material, the distance between the luminophore and the host material can be increased, and energy transfer due to the Dexter mechanism can be suppressed. Further, it is preferable that the tBu group is arranged so as to cover a luminophore such as an anthracene ring.

<Reason for using a phosphorescent material having a 5-membered ring skeleton>
Next, let's consider energy donors. The present inventors have discovered that energy transfer by the Förster mechanism can be effectively utilized by using a material having a five-membered ring skeleton as a phosphorescent material used as an energy donor. As described later, a phosphorescent material having a five-membered ring skeleton can be suitably used as a bulky energy donor.

The five-membered ring skeleton is preferably a heteroaromatic ring skeleton, such as a pyrrole skeleton, a pyrazole skeleton, an imidazole skeleton, a triazole skeleton or a tetrazole skeleton, a benzimidazole skeleton, a naphthoimidazole skeleton, and the like. In particular, phosphorescent materials having an imidazole skeleton, triazole skeleton, benzimidazole skeleton, or naphthoimidazole skeleton are preferable, and metal complexes having this skeleton as a ligand are particularly preferable, and metal complexes having this skeleton as a ligand and as a central metal are particularly preferable. It is preferable to have metals of groups 8 to 10 and periods 5 and 6 (Ru, Rh, Pd, Os, Ir, or Pt), and Ir complexes are particularly preferable. Note that the benzimidazole skeleton and the naphthoimidazole skeleton are examples of skeletons having an imidazole skeleton.

Phosphorescent materials having a five-membered ring skeleton as a ligand tend to have a high HOMO level. In the case where a material with a high HOMO level is used as the above-mentioned compound 133 (energy donor) in the light emitting layer 130, when a current is passed through the light emitting device 150, the compound 132 which is the guest material (energy acceptor) is positively affected. It is possible to suppress the pores from being trapped, that is, it is possible to suppress the compound 132 from being positively charged. Excitation of a compound by an electric current is caused by the trapping of holes and electrons on the same molecule, except for the above-mentioned exciplexes. Therefore, by using a material with a high HOMO level for the compound 133, current excitation on the compound 132 (direct excitation of the compound 132) can be suppressed. When compound 132 is directly excited, since compound 132 is a fluorescent material, the generated triplet excitons do not contribute to light emission, leading to a decrease in light emission efficiency. Therefore, when the HOMO level of the phosphorescent material having a five-membered ring skeleton is high, by using the phosphorescent material as the compound 133, a decrease in the luminous efficiency of the light emitting device 150 can be suppressed.

<Phosphorescent material with 5-membered ring skeleton as bulky energy donor>
Here, as a phosphorescent material having a 5-membered ring skeleton as a ligand that can be used in one embodiment of the present invention, an example of an Ir complex having a 5-membered ring skeleton as a ligand is shown below. Ir(mpptz-diPrp) ₃ has a triazole skeleton as a five-membered ring skeleton, and fac-Ir(pbi-diBup) ₃ is an Ir complex having an imidazole skeleton.

Like the above-mentioned Ir complex, when a skeleton containing two or more nitrogen atoms in the five-membered ring skeleton, such as an imidazole skeleton or a triazole skeleton, is used as the five-membered ring skeleton of the ligand, coordination with the metal is possible. There is nitrogen that does not. At least one nitrogen that does not coordinate with the metal does not participate in a double bond, so it can have a substituent while maintaining an aromatic ring (in the above-mentioned Ir complex, the nitrogen atom is circled). Examples of the substituent include various substituents such as hydrogen, an alkyl group, and an aromatic hydrocarbon group, but a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms is preferred. Particularly preferred is an unsubstituted phenyl group or a phenyl group having one or more alkyl groups having 1 to 6 carbon atoms. Further, an electron-withdrawing group such as fluorine, a cyano group, or a fluorinated alkyl group may be further bonded to the phenyl group. With this configuration, the thermal stability and sublimability of the Ir complex can be improved.

Therefore, when using a compound having a 5-membered ring skeleton as a ligand of an Ir complex, it is desirable that the nitrogen atom has a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms as a substituent. It will be done. By having this substituent, the ligand becomes a bulky structure with large steric hindrance. As a result, the Ir complex assumes a bulky structure. In other words, when a compound having a five-membered ring skeleton is used as a ligand for a phosphorescent material, the Ir complex tends to have a bulky structure.

Now, consider the case where the Ir complex is excited. In Ir complexes that are phosphorescent materials, the lowest triplet excited level is often derived from triplet MLCT. Therefore, triplet excitation energy often exists near the Ir atom and the part of the ligand that is coordinated to the Ir atom (nitrogen atom coordinated to Ir or orthometalized carbon atom). .

Here, a case will be considered in which an Ir complex having a bulky ligand is dispersed in the light emitting layer. Because of the bulky ligand, the distance between the Ir atom in the Ir complex and the material surrounding the Ir complex can be increased. That is, deactivation of triplet excitation energy due to the Dexter mechanism can be suppressed.

Here, the case where the bulky Ir complex is used for the above-mentioned compound 133 will be considered. As described above, the deactivation of excitation energy from compound 133 to compound 132 due to the Dexter mechanism (route A ₃ ) can be suppressed. Therefore, energy transfer via route _A2 (energy transfer via the Förster mechanism) can be efficiently utilized. From the above, by using an Ir complex having a 5-membered ring skeleton as a ligand, a light-emitting device with high luminous efficiency can be obtained.

Further, as described above, by using an Ir complex having a five-membered ring skeleton as a ligand as an energy donor, transfer of excitation energy due to the Dexter mechanism can be suppressed. Therefore, when an Ir complex having a 5-membered ring as a ligand is used as an energy donor, even if the energy acceptor as a guest material has a small number of protecting groups, energy transfer via route _A2 can be efficiently utilized. be able to. In this case, the energy acceptor preferably has at least two protecting groups for one luminophore, more preferably three or more, and even more preferably four or more. The five-membered ring skeleton used for the ligand of the Ir complex is preferably an imidazole skeleton or a triazole skeleton. Furthermore, it is more preferable that the Ir complex has a structure in which a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms is bonded as a substituent to a nitrogen atom that does not bond to Ir and does not participate in double bonds. . Further, when the aromatic hydrocarbon group is a phenyl group and the phenyl group has a substituent, it is more preferable to have an alkyl group having 1 to 6 carbon atoms as the substituent.

Specific examples of the aromatic hydrocarbon group having 6 to 13 carbon atoms include phenyl group, biphenyl group, naphthyl group, and fluorenyl group. In addition, examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, pentyl group, hexyl group, cyclohexyl group, norbornyl group, adamantyl group, isopropyl group, sec-butyl group, isobutyl group, tert- Butyl group, isopentyl group, sec-pentyl group, tert-pentyl group, neopentyl group, isohexyl group, 3-methylpentyl group, 2-methylpentyl group, 2-ethylbutyl group, 1,2-dimethylbutyl group, 2,3 -dimethylbutyl group, etc. Note that the aromatic hydrocarbon group having 6 to 13 carbon atoms and the alkyl group having 1 to 6 carbon atoms are not limited to these.

Further, the triplet excitation energy of Ir complexes having a 5-membered ring skeleton as a ligand tends to be higher than that of Ir complexes composed only of 6-membered ring skeletons. Therefore, when a fluorescent material exhibiting relatively short wavelength light emission such as green or blue light is used as an energy acceptor as Compound 132, an Ir complex having a 5-membered ring skeleton as a ligand can be suitably used as an energy donor. can.

As will be explained later, in energy transfer by the Förster mechanism, the absorption spectrum of the energy acceptor (the absorption band on the longest wavelength side (mainly the absorption band originating from the S1 level)) and the emission spectrum of the energy donor It is preferable that the overlap is large. When using a fluorescent material that has an emission peak on the relatively short wavelength side (400 nm to 580 nm) from blue to green, the absorption band of the fluorescent material also exists on the short wavelength side. Therefore, in order to increase the overlap between the absorption band and the emission spectrum of the energy donor, it is preferable to use an energy donor with a large triplet excitation energy.

In addition, by using a phosphorescent material having a five-membered ring skeleton for compound 133, it is possible to efficiently utilize energy transfer by Förster mechanism while suppressing energy transfer by Dexter mechanism. When added to the light emitting layer 130, its concentration can be increased. As a result, it is possible to suppress the energy transfer due to the Dexter mechanism while increasing the energy transfer rate due to the Förster mechanism, which are originally contradictory phenomena. The concentration of compound 133 is preferably 2 wt% or more and 30 wt% or less, more preferably 5 wt% or more and 20 wt% or less, and even more preferably 5 wt% or more and 15 wt% or less, based on the host material. With this configuration, the speed of energy transfer by the Förster mechanism can be increased, so a light emitting device with high luminous efficiency can be obtained. Furthermore, since luminous efficiency can be improved by using a highly stable fluorescent material, a highly reliable light emitting device can be manufactured. Further, it is preferable that the concentrations of both compound 133 and compound 132, which is a fluorescent material, are high. Further, it is preferable that the concentrations of compound 133 and compound 132 be as high as possible. Specifically, the concentration ratio of compound 133 and compound 132 is preferably 1:0.2 or more and 1:5 or less, more preferably 1:0.5 or more and 1:2 or less.

<Configuration example 2 of light emitting layer>
FIG. 4C is an example of the correlation of energy levels in the light emitting layer 130 of the light emitting device 150 according to one embodiment of the present invention. The light emitting layer 130 shown in FIG. 4A includes a compound 131, a compound 132, and a compound 133. In one aspect of the invention, compound 132 is preferably a fluorescent material. Furthermore, in this configuration example, compound 131 and compound 133 are a combination that forms an exciplex. Note that the case where the compound 133 is a phosphorescent material having a five-membered ring skeleton will be described below.

The combination of Compound 131 and Compound 133 may be any combination that can form an exciplex, but one must be a compound that has the function of transporting holes (hole transporting property) and the other is a compound that can transport electrons. A compound having a transporting function (electron transporting property) is more preferable. In this case, it becomes easier to form a donor-acceptor type exciplex, and the exciplex can be formed efficiently. Further, when the combination of compound 131 and compound 133 is a combination of a compound having a hole transporting property and a compound having an electron transporting property, the carrier balance can be easily controlled by the mixing ratio. Specifically, the ratio of compound having hole transporting property to compound having electron transporting property is preferably in the range of 1:9 to 9:1 (weight ratio). Moreover, by having this configuration, the carrier balance can be easily controlled, so that the carrier recombination region can also be easily controlled. A phosphorescent material having a five-membered ring skeleton tends to have a high HOMO level. Therefore, it can be suitably used as a material having hole transport properties.

In addition, as a combination of host materials that efficiently forms an exciplex, the HOMO level of one of Compound 131 and Compound 133 is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other. It is preferable. Note that the HOMO level of compound 131 may be equivalent to the HOMO level of compound 133, or the LUMO level of compound 131 may be equivalent to the LUMO level of compound 133.

Note that the LUMO level and HOMO level of a compound can be derived from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by cyclic voltammetry (CV) measurement.

For example, when compound 133 has hole transport properties and compound 131 has electron transport properties, the HOMO level of compound 133 is higher than the HOMO level of compound 131, as shown in the energy band diagram shown in FIG. 4B. is preferable, and it is preferable that the LUMO level of compound 133 is higher than that of compound 131. With such a correlation of energy levels, holes and electrons, which are carriers injected from a pair of electrodes (electrode 101 and electrode 102), are easily injected into compound 133 and compound 131, respectively, which is preferable. be.

In addition, in FIG. 4B, Comp (131) represents compound 131, Comp (133) represents compound 133, ΔE _C1 represents the energy difference between the LUMO level and HOMO level of compound 131, and ΔE _C3 represents the compound 131. ΔE represents the energy difference between the LUMO level and the HOMO level of compound 133, and _ΔE is a notation and code representing the energy difference between the LUMO level of compound 131 and the HOMO level of compound 133.

Further, the exciplex formed by compound 131 and compound 133 is an exciplex in which compound 133 has a HOMO molecular orbital and compound 131 has a LUMO molecular orbital. In addition, the excitation energy of the exciplex approximately corresponds to the energy difference (ΔE _E ) between the LUMO level of compound 131 and the HOMO level of compound 133, and the energy difference between the LUMO level and HOMO level of compound 131. (ΔE _C1 ) and the energy difference between the LUMO level and the HOMO level of compound 133 (ΔE _C3 ). Therefore, by forming an exciplex with compound 131 and compound 133, an excited state can be formed with lower excitation energy. Also, because it has a lower excitation energy, the exciplex can form a stable excited state.

Further, FIG. 4C shows the correlation between the energy levels of the compound 131, the compound 132, and the compound 133 in the light-emitting layer 130. Note that the notations and symbols in FIG. 4C are as follows.
・Comp (131): Compound 131
・Comp (133): Compound 133
・Guest (132): Compound 132
・S _C1 : S1 level of compound 131 ・T _C1 : T1 level of compound 131 ・S _C3 : S1 level of compound 133 ・_TC3 : S1 level of compound 133 ・S _G : S1 level of compound 132・_TG : T1 level of compound 132 ・_SE : S1 level of exciplex ・_TE : T1 level of exciplex

In the light-emitting device of one embodiment of the present invention, the compound 131 and the compound 133 included in the light-emitting layer 130 form an exciplex. The S1 level (S _E ) of the exciplex and the T1 level (T _E ) of the exciplex are energy levels adjacent to each other (see Route A ₄ in FIG. 4C).

The excitation energy levels (S _E and T _E ) of the exciplex are lower than the S1 levels (S _C1 and S _C3 ) of each substance forming the exciplex (Compound 131 and Compound 133), so the excitation energy levels are lower. It becomes possible to form an excited state. Thereby, the driving voltage of the light emitting device 150 can be reduced.

Since the S1 level (S _E ) and T1 level (T _E ) of the exciplex are energy levels adjacent to each other, they are likely to undergo inverse intersystem crossing and have TADF properties. Therefore, the exciplex has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A ₅ in FIG. 4C). Singlet excitation energy possessed by the exciplex can be quickly transferred to compound 132. (Figure 4C route A ₆ ). At this time, it is preferable that S _E ≧ _SG . In route A ₆ , the exciplex is the energy donor and compound 132 acts as the energy acceptor. Specifically, a tangent line is drawn at the tail of the short wavelength side of the fluorescence spectrum of the exciplex, the energy of the wavelength of the extrapolated line is set as _SE , and the energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 or the fluorescence spectrum is When a tangent line is drawn at the hem on the short wavelength side and the energy of the wavelength of the extrapolated line is S _G , it is preferable that S _E ≧S _G.

Note that, in order to improve the TADF property, it is preferable that the T1 levels of both Compound 131 and Compound 133, that is, T _C1 and T _C3 , are T _E or higher. As an indicator thereof, it is preferable that the emission peak wavelengths on the shortest wavelength side of the phosphorescence spectra of Compound 131 and Compound 133 are both equal to or less than the maximum emission peak wavelength of the exciplex. Alternatively, draw a tangent at the short wavelength side of the emission spectrum of the exciplex, set the energy of the wavelength of the extrapolated line as _TE , and draw tangents at the short wavelength side of the phosphorescence spectra of Compound 131 and Compound 133. , it is preferable that T _E −T _C1 ≦0.2eV and T _E −T _C3 ≦0.2eV, where the energy of the wavelength of the extrapolated line is T C1 and _{T C3} of each compound. .

Further, in this configuration example, a compound having a heavy atom is used as one of the compounds forming the exciplex. Therefore, intersystem crossing between the singlet state and the triplet state is promoted. Therefore, an exciplex capable of converting triplet excited state energy into light emission can be formed. In this case, the triplet excitation energy level ( _TE ) of the exciplex can be the energy donor level, so it is necessary that _TE is higher than the singlet excitation energy level (S _G ) of compound 132, which is the luminescent material. preferable. Specifically, a tangent line is drawn at the tail of the short wavelength side of the emission spectrum of the exciplex using heavy atoms, the energy of the wavelength of the extrapolated line is taken as _TE , and the wavelength of the absorption edge of the absorption spectrum of compound 132 is When a tangent is drawn at the tail of the short wavelength side of the energy or emission spectrum and the energy of the wavelength of the extrapolated value is _SG , it is preferable that T _E ≧ _SG .

By establishing such a correlation between energy levels, the triplet excitation energy of the generated exciplex can be directly derived from the triplet excitation energy level (T _E ) of the exciplex or from the singlet excitation energy level (S _E ). Energy can be transferred to the singlet excitation energy level (S _G ) of compound 132 through . Note that since the S1 level ( _SE ) and T1 level ( _TE ) of the exciplex are energy levels adjacent to each other, it is difficult to clearly distinguish between fluorescence and phosphorescence in the emission spectrum. There is. In that case, it may be possible to distinguish between fluorescence and phosphorescence depending on the emission lifetime.

The triplet excitation energy generated in the light emitting layer 130 passes through the above route A ₄ and energy transfer from the S1 level of the exciplex to the S1 level of the guest material (route A ₆ ), causing the guest material to emit light. be able to. Therefore, by using a combination of materials that form an exciplex in the light emitting layer 130, the light emitting efficiency of the fluorescent light emitting device can be increased.

Note that the compound having a heavy atom used in the above structure preferably contains a heavy atom such as Ir, Pt, Os, Ru, or Pd. Moreover, the compound having the heavy atom is preferably a phosphorescent material. On the other hand, in this configuration example, since the phosphorescent material is one of the materials constituting the exciplex that acts as an energy donor, the quantum yield may be high or low. That is, energy transfer from the triplet excitation energy level of the exciplex directly or via the singlet excitation energy level to the singlet excitation energy level of the guest material is sufficient as an allowable transition. Energy transfer from the above-mentioned exciplexes made of phosphorescent materials or phosphorescent materials to the guest material is from the triplet excitation energy level of the energy donor to the singlet excitation energy level of the guest material (energy acceptor). This is preferable because the energy transfer to is an allowed transition. Therefore, there is also a path in which the triplet excitation energy of the exciplex is transferred to the S1 level (S _G ) of the guest material through the process of route A ₆ without going through the process of route A ₅ in FIG. 4C. In route A ₆ , the exciplex is the energy donor and compound 132 acts as the energy acceptor.

Here, in the light-emitting device that is one embodiment of the present invention, a guest material having a protecting group on the luminophore is used as the compound 132. With this configuration, as described above, energy transfer due to the Dexter mechanism represented by route A ₇ can be suppressed, and deactivation of triplet excitation energy can be suppressed. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

Further, in one embodiment of the present invention, a phosphorescent material having a five-membered ring skeleton is used. With this configuration, as described above, energy transfer due to the Dexter mechanism represented by route A ₇ can be suppressed, and deactivation of triplet excitation energy can be suppressed. Further, recombination of carriers in the compound 132 can be suppressed. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

The processes of routes A ₄ to A ₆ shown above may be referred to as Exciplex-Singlet Energy Transfer (ExSET) or Exciplex-Enhanced Fluorescence (ExEF) in this specification and the like. In other words, in the light emitting layer 130, excitation energy is donated from the exciplex to the fluorescent material.

<Configuration example 3 of light emitting layer>
FIG. 5A shows a case where four types of materials are used for the light emitting layer 130. In FIG. 5A, the light emitting layer 130 includes a compound 131, a compound 132, a compound 133, and a compound 134. In one embodiment of the present invention, compound 133 has a function of converting triplet excitation energy into luminescence. In this configuration example, a case where the compound 133 is a phosphorescent material having a five-membered ring skeleton will be described. Compound 132 is a guest material that emits fluorescence. Furthermore, compound 131 is an organic compound that forms an exciplex with compound 134.

Further, FIG. 5B shows the correlation between the energy levels of the compound 131, the compound 132, the compound 133, and the compound 134 in the light-emitting layer 130. Note that the notations and symbols in FIG. 5B are as follows, and other notations and symbols are the same as those shown in FIG. 2B.
・S _C4 : S1 level of compound 134 ・T _C4 : T1 level of compound 134

In the light-emitting device of one embodiment of the present invention shown in this structure example, the compound 131 and the compound 134 included in the light-emitting layer 130 form an exciplex. The S1 level (S _E ) of the exciplex and the T1 level (T _E ) of the exciplex are energy levels adjacent to each other (see route A ₈ in FIG. 5B).

As mentioned above, the exciplex produced by the above process loses excitation energy, so that the two substances that had formed the exciplex behave as original separate substances.

The excitation energy levels (S _E and T _E ) of the exciplex are lower than the S1 levels (S _C1 and S _C4 ) of each substance forming the exciplex (Compound 131 and Compound 134), so the excitation energy levels are lower. It becomes possible to form an excited state. Thereby, the driving voltage of the light emitting device 150 can be reduced.

Here, when the compound 133 is a phosphorescent material, intersystem crossing between the singlet state and the triplet state is allowed. Therefore, both the singlet excitation energy and triplet excitation energy possessed by the exciplex rapidly move to compound 133 (route A ₉ ). At this time, it is preferable that T _E ≧T _C3 . Moreover, the triplet excitation energy of compound 133 can be efficiently converted into the singlet excitation energy of compound 132 (route A ₁₀ ). Here, as shown in FIG. 5B, it is preferable that T _E ≧ _TC3 ≧ _SG because the excitation energy of the compound 133 is efficiently transferred as singlet excitation energy to the compound 132 that is the guest material. Specifically, a tangent line is drawn at the tail of the short wavelength side of the phosphorescence spectrum of compound 133, the energy of the wavelength of the extrapolated line is set as T _C3 , and the energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 or the fluorescence spectrum is When a tangent line is drawn at the hem on the short wavelength side and the energy of the wavelength of the extrapolated line is S _G , it is preferable that T _C3 ≧S _G. In route A ₁₀ , compound 133 functions as an energy donor and compound 132 functions as an energy acceptor.

At this time, the combination of compound 131 and compound 134 may be any combination that can form an exciplex, but one of the compounds has a hole transporting property and the other has an electron transporting property. It is more preferable that

In addition, as a combination of materials that can efficiently form an exciplex, the HOMO level of one of compounds 131 and 134 is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other. is preferred.

Further, the correlation between the energy levels of the compound 131 and the compound 134 is not limited to that shown in FIG. 5B. That is, the singlet excitation energy level (S _C1 ) of compound 131 may be higher or lower than the singlet excitation energy level (S _C4 ) of compound 134. Further, the triplet excitation energy level (T _C1 ) of compound 131 may be higher or lower than the triplet excitation energy level (T _C4 ) of compound 134.

Further, in the light-emitting device according to one embodiment of the present invention, compound 131 preferably has a π electron-deficient skeleton. With this configuration, the LUMO level of compound 131 becomes low, making it suitable for forming an exciplex.

Further, in the light-emitting device according to one embodiment of the present invention, compound 131 preferably has a π electron-excessive skeleton. With this configuration, the HOMO level of compound 131 becomes high, making it suitable for forming an exciplex.

Here, in the light-emitting device that is one embodiment of the present invention, a guest material having a protecting group on the luminophore is used as the compound 132. With this configuration, as described above, it is possible to suppress energy transfer due to the Dexter mechanism represented by root A ₁₁ and suppress deactivation of triplet excitation energy. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

Further, in one embodiment of the present invention, a phosphorescent material having a five-membered ring skeleton is used for compound 133. With this configuration, as described above, it is possible to suppress energy transfer due to the Dexter mechanism represented by root A ₁₁ and suppress deactivation of triplet excitation energy. Further, recombination of carriers in the compound 132 can be suppressed. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

Note that the processes of routes A ₈ and A ₉ shown above may be referred to as ExTET (Exciplex-Triplet Energy Transfer) in this specification and the like. In other words, in the light emitting layer 130, excitation energy is supplied from the exciplex to the compound 133. Therefore, this configuration example can be said to be a configuration in which a fluorescent material having a protecting group is mixed in a light emitting layer that can utilize ExTET.

<Example 4 of structure of light emitting layer>
In this structural example, a case will be described in which a material having TADF properties is used as the compound 134 described in the above-mentioned structural example 3 of the light emitting layer.

FIG. 5C shows a case where four types of materials are used for the light emitting layer 130. In FIG. 5C, the light emitting layer 130 includes a compound 131, a compound 132, a compound 133, and a compound 134. In one embodiment of the present invention, compound 133 has the ability to convert triplet excitation energy into luminescence. Compound 132 is a guest material that emits fluorescence. Furthermore, compound 131 is an organic compound that forms an exciplex with compound 134. Further, in this configuration example, a case will be described in which the compound 133 is a phosphorescent material having a five-membered ring skeleton.

Here, since the compound 134 is a TADF material, the compound 134 that does not form an exciplex has a function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A ₁₂ in FIG. 5C). Singlet excitation energy possessed by compound 134 can be quickly transferred to compound 132. (Figure 5C route A ₁₃ ). At this time, it is preferable that S _C4 ≧ _SG . Specifically, a tangent line is drawn at the tail of the shorter wavelength side of the fluorescence spectrum of compound 134, and the energy of the wavelength of the extrapolated line is set as _SC4 , and the energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 or the fluorescence spectrum is When a tangent line is drawn at the hem on the short wavelength side and the energy of the wavelength of the extrapolated line is S _G , it is preferable that S _C4 ≧S _G.

Similar to the previous structure example of the light-emitting layer, in the light-emitting device of one embodiment of the present invention, triplet excitation energy is transferred to the guest material compound 132 via routes A ₈ to A ₁₀ in FIG. 5B. There is a route to compound 132 via route A ₁₂ and route A ₁₃ in FIG. 5C. The presence of multiple paths through which triplet excitation energy moves to the fluorescent material can further improve luminous efficiency. In route A ₁₀ , compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. Further, in route A ₁₃ , compound 134 functions as an energy donor, and compound 132 functions as an energy acceptor.

Here, in the light-emitting device that is one embodiment of the present invention, a guest material having a protecting group on the luminophore is used as the compound 132. With this configuration, as described above, it is possible to suppress energy transfer due to the Dexter mechanism represented by root A ₁₁ and suppress deactivation of triplet excitation energy. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

Further, in one embodiment of the present invention, a phosphorescent material having a five-membered ring skeleton is used for compound 133. With this configuration, as described above, it is possible to suppress energy transfer due to the Dexter mechanism represented by root A ₁₁ and suppress deactivation of triplet excitation energy. Further, recombination of carriers in the compound 132 can be suppressed. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

<Energy transfer mechanism>
Here, the Förster mechanism and the Dexter mechanism will be explained. Here, regarding the provision of excitation energy from the first material in the excited state to the second material in the ground state, we will explain the energy transfer process between the molecules of the first material and the second material. The same applies when either one is an exciplex.

≪Förster mechanism≫
In the Förster mechanism, energy transfer does not require direct contact between molecules, and energy transfer occurs through the resonance phenomenon of dipole vibrations of the first material and the second material. The first material transfers energy to the second material by the resonance phenomenon of dipole vibration, and the first material in an excited state becomes a ground state, and the second material in a ground state becomes an excited state. Note that the rate constant _kh*→g of the Förster mechanism is shown in equation (1).

In formula (1), ν represents the vibration frequency, and f' _h (ν) is the normalized emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, triplet phosphorescence spectrum when discussing energy transfer from an excited state), ε _g (ν) represents the molar extinction coefficient of the second material, N represents Avogadro's number, and n is the refractive index of the medium. , R represents the intermolecular distance between the first material and the second material, τ represents the actually measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), c represents the speed of light, and φ represents the emission quantum yield (fluorescence quantum yield when discussing energy transfer from the singlet excited state, phosphorescence quantum yield when discussing energy transfer from the triplet excited state), and K ² is the first is a coefficient (0 to 4) representing the orientation of the transition dipole moment of the material and the second material. Note that in the case of random orientation, K ² =2/3.

≪Dexter mechanism≫
In the Dexter mechanism, the first material and the second material approach an effective contact distance that causes their orbits to overlap, and energy is generated through the exchange of electrons between the first material's electrons in the excited state and the second material's ground state. Movement occurs. Note that the rate constant _kh*→g of the Dexter mechanism is shown in equation (2).

In formula (2), h is Planck's constant, K is a constant with an energy dimension, ν represents the frequency, and f' _h (ν) is the normalized value of the first material. represents the emission spectrum (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), and ε' _g (ν) is the emission spectrum of the second material. It represents a normalized absorption spectrum, where L represents the effective molecular radius and R represents the intermolecular distance between the first material and the second material.

Here, the energy transfer efficiency φ _ET from the first material to the second material is expressed by equation (3). k _r represents the rate constant of the luminescence process of the first material (fluorescence when discussing energy transfer from a singlet excited state, phosphorescence when discussing energy transfer from a triplet excited state), and k _n is represents the rate constant of a non-luminescent process (thermal deactivation or intersystem crossing) of the second material, and τ represents the actually measured lifetime of the excited state of the first material.

From formula (3), in order to increase the energy transfer efficiency φ _ET , the energy transfer rate constant k _h*→g should be increased, and the other competing rate constants k _r +k _n (=1/τ) should be It turns out that the smaller the size, the better.

≪Concepts for increasing energy transfer≫
First, consider energy transfer by the Förster mechanism. By substituting equation (1) into equation (3), τ can be eliminated. Therefore, for the Förster mechanism, the energy transfer efficiency φ _ET does not depend on the lifetime τ of the excited state of the first material. Furthermore, it can be said that the energy transfer efficiency φ _ET is better as the emission quantum yield φ is higher.

Further, it is preferable that the emission spectrum of the first material and the absorption spectrum of the second material (absorption corresponding to the transition from the singlet ground state to the singlet excited state) overlap greatly. Furthermore, it is preferable that the second material also has a high molar absorption coefficient. This means that the emission spectrum of the first material and the absorption band appearing on the longest wavelength side of the second material overlap. Note that since a direct transition from the singlet ground state to the triplet excited state in the second material is prohibited, the molar extinction coefficient associated with the triplet excited state in the second material is a negligible amount. From this, the energy transfer process from the excited state of the first material to the triplet excited state of the second material due to the Förster mechanism can be ignored, and only the energy transfer process to the singlet excited state of the second material. Just consider it.

Further, the energy transfer rate due to the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material, according to equation (1). Further, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to increase the energy transfer rate due to the Förster mechanism while suppressing the energy transfer due to the Dexter mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Therefore, since the above-mentioned protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less.

Next, consider energy transfer by the Dexter mechanism. According to formula (2), in order to increase the rate constant _k When discussing migration, it is understood that the larger the overlap between the phosphorescence spectrum) and the absorption spectrum of the second material (absorption corresponding to the transition from the singlet ground state to the singlet excited state), the better. Therefore, optimization of energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band appearing on the longest wavelength side of the second material.

Furthermore, by substituting equation (2) into equation (3), it can be seen that the energy transfer efficiency φ _ET in the Dexter mechanism depends on τ. Since the Dexter mechanism is an energy transfer process based on electron exchange, energy transfer from the singlet excited state of the first material to the singlet excited state of the second material, as well as the triplet excited state of the first material Energy transfer from the state to the triplet excited state of the second material also occurs.

In the light-emitting device of one embodiment of the present invention, since the second material is a fluorescent material, the energy transfer efficiency of the second material to a triplet excited state is preferably low. That is, the energy transfer efficiency based on the Dexter mechanism from the first material to the second material is preferably low, and the energy transfer efficiency based on the Förster mechanism from the first material to the second material is preferably high. .

Moreover, as already mentioned, the energy transfer efficiency in the Förster mechanism does not depend on the lifetime τ of the excited state of the first material. On the other hand, the energy transfer efficiency in the Dexter mechanism depends on the excitation lifetime τ of the first material, and in order to reduce the energy transfer efficiency in the Dexter mechanism, the excitation lifetime τ of the first material is preferably short.

Therefore, one embodiment of the present invention uses an exciplex, a phosphorescent material, or a TADF material as the first material. These materials have the function of converting triplet excitation energy into luminescence. Since the energy transfer efficiency of the Förster mechanism depends on the emission quantum yield of the energy donor, the first material that can convert the triplet excited state to emission, such as a phosphorescent material, exciplex, or TADF material, Excitation energy can be transferred to the second material by a Förster mechanism. On the other hand, with the configuration of one embodiment of the present invention, reverse intersystem crossing from the triplet excited state of the first material (exciplex or TADF material) to the singlet excited state is promoted, and the triplet excitation of the first material The excitation lifetime τ of the state can be shortened. Furthermore, the transition from the triplet excited state of the first material (phosphorescent material or exciplex using the phosphorescent material) to the singlet ground state is promoted, and the excitation lifetime τ of the triplet excited state of the first material is can be shortened. As a result, the energy transfer efficiency in the Dexter mechanism from the triplet excited state of the first material to the triplet excited state of the fluorescent material (second material) can be reduced.

Further, in the light-emitting device of one embodiment of the present invention, a fluorescent material having a protecting group is used as the second material, as described above. Therefore, the intermolecular distance between the first material and the second material can be increased. Therefore, in the light-emitting device of one embodiment of the present invention, a material having a function of converting triplet excitation energy into light emission is used as the first material, and a fluorescent material having a protecting group is used as the second material. The efficiency of energy transfer in the mechanism can be reduced. As a result, non-radiative deactivation of triplet excitation energy in the light-emitting layer 130 can be suppressed, and a light-emitting device with high luminous efficiency can be provided.

<Materials>
Next, details of the components of the light emitting device according to one embodiment of the present invention will be described below.

≪Light-emitting layer≫
Each material that can be used for the light emitting layer 130 will be described below. The light-emitting layer of the light-emitting device according to one embodiment of the present invention uses an energy acceptor that has a function of converting triplet excitation energy into light emission and an energy donor that has a protecting group on the luminophore. Examples of materials having the function of converting triplet excitation energy into luminescence include TADF materials and phosphorescent materials.

Examples of the luminophore possessed by the compound 132 that functions as an energy acceptor include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, and the like. In particular, fluorescent compounds having a naphthalene skeleton, anthracene skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, or naphthobisbenzofuran skeleton are preferred because they have a high fluorescence quantum yield.

In addition, as a protecting group, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. is preferred.

Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, ethyl group, propyl group, pentyl group, and hexyl group, and branched alkyl groups having 3 to 10 carbon atoms, which will be described later, are particularly preferred. Note that the alkyl group is not limited to these.

Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group. The cycloalkyl group is not limited to these. In addition, when the cycloalkyl group has a substituent, the substituent includes a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, and hexyl group. Alkyl groups having 1 to 7 carbon atoms, such as cycloalkyl groups having 5 to 7 carbon atoms, such as cyclopentyl, cyclohexyl, cycloheptyl, 8,9,10-trinorbornanyl, and phenyl. Examples include aryl groups having 6 to 12 carbon atoms, such as Naphthyl group, Naphthyl group, and Biphenyl group.

Examples of the branched alkyl group having 3 to 10 carbon atoms include isopropyl group, sec-butyl group, isobutyl group, tert-butyl group, isopentyl group, sec-pentyl group, tert-pentyl group, neopentyl group, isohexyl group, 3 -methylpentyl group, 2-methylpentyl group, 2-ethylbutyl group, 1,2-dimethylbutyl group, 2,3-dimethylbutyl group and the like. The branched alkyl group is not limited to these.

Examples of the trialkylsilyl group having 3 to 12 carbon atoms include trimethylsilyl group, triethylsilyl group, and tert-butyldimethylsilyl group. The trialkylsilyl group is not limited to these.

The molecular structure of the energy acceptor is preferably such that a luminophore and two or more diarylamino groups are bonded, and each of the aryl groups of the diarylamino groups has at least one protecting group. More preferably, at least two protecting groups are attached to each of the aryl groups. This is because the larger the number of protecting groups, the greater the effect of suppressing energy transfer due to the Dexter mechanism when the guest material is used in the light emitting layer. Note that the diarylamino group is preferably a diphenylamino group in order to suppress an increase in molecular weight and maintain sublimation properties.

Furthermore, by bonding two or more amino groups to a luminophore, it is possible to obtain a fluorescent material with a high quantum yield while adjusting the emission color. Further, it is preferable that the amino group is bonded to a symmetrical position with respect to the luminophore. With this configuration, a fluorescent material having a high quantum yield can be obtained.

Furthermore, instead of directly introducing the protecting group into the luminophore, the protecting group may be introduced through the aryl group of the diarylamine. This configuration is preferable because it is possible to arrange the protecting group so as to cover the luminophore, so that the distance between the host material and the luminophore can be increased from any direction. Further, when a protecting group is not directly bonded to a luminophore, it is preferable to introduce four or more protecting groups to one luminophore.

Further, as shown in FIG. 3B, at least one of the atoms constituting the plurality of protecting groups is located directly above one surface of the luminophore, that is, the fused aromatic ring or the fused heteroaromatic ring, and the plurality of protecting groups A configuration in which at least one of the atoms constituting is located directly above the other surface of the fused aromatic ring or the fused heteroaromatic ring is preferred. As a specific method, the following configuration can be mentioned. That is, a fused aromatic ring or fused heteroaromatic ring that is a luminophore is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups are each independently protected at the 3-position and the 5-position. It is a structure having a group.

With this configuration, as shown in Figure 3B, the protecting group at the 3- or 5-position on the phenyl group is directly above the fused aromatic ring or fused heteroaromatic ring, which is the luminophore. Can take three-dimensional configuration. As a result, the upper and lower sides of the fused aromatic ring or fused heteroaromatic ring can be efficiently covered, and Dexter migration can be suppressed.

As the energy acceptor described above, an organic compound represented by the following general formula (G1) or (G2) can be suitably used.

In the general formulas (G1) and (G2), A represents a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms, and Ar ¹ to Ar ⁶ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms, and X ¹ to X ¹² each independently represents a branched alkyl group having 3 to 10 carbon atoms, substituted or unsubstituted represents any one of a cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms, and each of R ¹ to R ¹⁰ independently represents hydrogen, an alkyl group having 3 to 10 carbon atoms; represents any one of a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms.

Examples of the aromatic hydrocarbon group having 6 to 13 carbon atoms include phenyl group, biphenyl group, naphthyl group, and fluorenyl group. Note that the aromatic hydrocarbon group is not limited to these. In addition, when the aromatic hydrocarbon group has a substituent, the substituent includes a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group. , an alkyl group having 1 to 7 carbon atoms such as a hexyl group, and a cycloalkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and an 8,9,10-trinorbornanyl group. and aryl groups having 6 to 12 carbon atoms such as phenyl group, naphthyl group, and biphenyl group.

In general formula (G1), the substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or the substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms represents the above-mentioned luminophore, and the above-mentioned skeleton is used. be able to. Moreover, in general formulas (G1) and (G2), X ¹ to X ¹² represent a protecting group.

Further, in the general formula (G2), the protecting group is bonded to the quinacridone skeleton, which is a luminophore, via an arylene group. With this configuration, the protecting group can be placed so as to cover the luminophore, so that energy transfer due to the Dexter mechanism can be suppressed. Note that it may have a protecting group that directly binds to the luminophore.

Further, as the energy acceptor, an organic compound represented by the following general formula (G3) or (G4) can be suitably used.

In general formulas (G3) and (G4), A represents a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having ¹⁰ to 30 carbon ^atoms. Each independently represents any one of a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms. .

It is also preferred that the protecting group is bonded to the luminophore via a phenyl group. With this configuration, the protecting group can be placed so as to cover the luminophore, so that energy transfer due to the Dexter mechanism can be suppressed. In addition, when a luminophore and a protecting group are bonded via a phenylene group, and two protecting groups are bonded to the phenylene group, as shown in general formulas (G3) and (G4), the two protecting groups are Preferably, it is bonded at the meta position relative to the phenylene group. With this configuration, the luminophore can be efficiently covered, so that energy transfer due to the Dexter mechanism can be suppressed. An example of the organic compound represented by the general formula (G3) is the above-mentioned 2tBu-mmtBuDPhA2Anth. That is, in one aspect of the present invention, (G3) is a particularly preferred example.

Further, as the energy acceptor, an organic compound represented by the following general formula (G5) can be suitably used.

In general formula (G5), X ¹ to X ⁸ each independently represent a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms. Represents any one of the following trialkylsilyl groups, R ¹¹ to R ¹⁸ each independently represent hydrogen, a branched alkyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted cyclocarbon having 3 to 10 carbon atoms. It represents any one of an alkyl group, a trialkylsilyl group having 3 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

Examples of the aryl group having 6 to 25 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and a spirofluorenyl group. Note that the aryl group having 6 or more and 25 or less carbon atoms is not limited to these. In addition, when the aryl group has a substituent, the above-mentioned alkyl group having 1 to 10 carbon atoms, branched alkyl group having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms; group, and a trialkylsilyl group having 3 or more and 10 or less carbon atoms.

Since the anthracene compound has a high emission quantum yield and a small area of the luminophore, the upper and lower sides of the anthracene surface can be efficiently covered with the protecting group. An example of the organic compound represented by general formula (G5) is the above-mentioned 2tBu-mmtBuDPhA2Anth.

Examples of compounds represented by general formulas (G1) to (G5) are shown below as structural formulas (102) to (105) and (200) to (249). In addition, the compounds mentioned in general formulas (G1) to (G5) are not limited to these. Further, the compounds represented by Structural Formulas (102) to (105) and (200) to (249) can be suitably used as a guest material of the light-emitting device of one embodiment of the present invention. Note that the guest material is not limited to these.

Furthermore, structural formulas (100) and (101) show examples of materials that can be suitably used as a guest material in the light-emitting device of one embodiment of the present invention. Note that the guest material is not limited to these.

Further, as the compound 133, a phosphorescent material having a five-membered ring skeleton can be used. Examples of the phosphorescent material include iridium, rhodium, or platinum-based organometallic complexes or metal complexes. Further, examples include platinum complexes and organic iridium complexes having porphyrin ligands, and among them, organic iridium complexes such as iridium-based orthometal complexes are preferred. Examples of the orthometallated ligands include pyrrole ligands, pyrazole ligands, 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, benzimidazole ligands, naphthoimidazole ligands, etc. can be mentioned. In this case, compound 133 (phosphorescent material) has an absorption band of triplet MLCT (Metal to Ligand Charge Transfer) transition. Further, it is preferable to select compound 133 and compound 132 (fluorescent material) so that the emission peak of compound 133 overlaps with the absorption band on the longest wavelength side (lower energy side) of compound 132 (fluorescent material). Thereby, a light emitting device with dramatically improved luminous efficiency can be obtained. Furthermore, even if the compound 133 is a phosphorescent material, it may form an exciplex with the compound 131. When forming an exciplex, the phosphorescent material does not need to emit light at room temperature, but only needs to be able to emit light at room temperature when the exciplex is formed. In this case, for example, tris[2-(1H-pyrazol-1-yl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(ppz) ₃ ) can be used as the phosphorescent material.

Examples of substances having an emission peak in blue or green include tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3 -yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp) ₃ ), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) ) (abbreviation: Ir(Mptz) ₃ ), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPrptz- 3b) ₃ ), Tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPr5btz) ₃ ), Tris{2 -[4-(4-cyano-2,6-diisobutylphenyl)-5-(2-methylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-diBuCNp) ₃ ), tris{2-[5-(2-methylphenyl)-4-(2,6-diisopropylphenyl)-4H-1,2,4-triazol-3-yl -κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-diPrp) ₃ ), an organometallic iridium complex having a 4H-triazole skeleton, and tris[3-methyl-1-(2-methylphenyl). )-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(Mptz1-mp) ₃ ), tris(1-methyl-5-phenyl-3-propyl-1H-1, Organometallic iridium complexes having a 1H-triazole skeleton such as 2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me) ₃ ) and fac-tris[1-(2,6-diisopropylphenyl) -2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi) ₃ ), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridium Organometallic iridium complexes having an imidazole skeleton such as Ir(dmpimpt-Me) ₃ ) and tris{2-[1-(4-cyano-2,6-diisobutylphenyl)- 1H-benzimidazol-2-yl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(pbi-diBuCNp) ₃ ), (OC-6-22)-tris{2-[1-(2,6 -diisobutylphenyl)-1H-benzimidazol-2-yl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(pbi-diBup) ₃ ), an organometallic iridium complex having a benzimidazole skeleton, {2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN3]phenyl-κC}[2-(4-methyl-5-phenyl-2 -pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(pni-diBup) ₂ (mdppy)), tris{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1, Examples include organometallic iridium complexes having a naphthoimidazole skeleton, such as 2-d]imidazol-2-yl-κN3]phenyl-κC}iridium (III) (abbreviation: Ir(pni-diBup) ₃ ). Among the above-mentioned, organometallic iridium complexes having nitrogen-containing five-membered heterocyclic skeletons such as 4H-triazole skeleton, 1H-triazole skeleton, imidazole skeleton, benzimidazole skeleton, and naphthoimidazole skeleton have high triplet excitation energy. , is particularly preferable because it has excellent reliability and luminous efficiency. In addition, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (abbreviation: PtOEP) and tris[1-(2-thenoyl) Rare earth metal complexes such as -3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: Eu(TTA) ₃ (Phen)) can also be used.

Further, as the compound 134, for example, a TADF material can be used. The energy difference between the S1 level and the T1 level of compound 134 is preferably small, and specifically is greater than 0 eV and less than 0.2 eV.

Compound 134 preferably has a skeleton having hole transporting properties and a skeleton having electron transporting properties. Alternatively, compound 134 preferably has a π-electron-rich skeleton or an aromatic amine skeleton and a π-electron-deficient skeleton. By doing so, it becomes easier to form a donor-acceptor type excited state within the molecule. Further, it is preferable that the compound 134 has a structure in which a skeleton having an electron transporting property and a skeleton having a hole transporting property are directly bonded so that both the donor property and the acceptor property are strong within the molecule. Alternatively, it is preferable to have a structure in which the π-electron-rich skeleton or the aromatic amine skeleton and the π-electron-deficient skeleton are directly bonded. By strengthening both donor and acceptor properties within the molecule, the overlap between the region where the molecular orbitals in the HOMO of compound 134 are distributed and the region where the molecular orbitals in the LUMO are distributed can be reduced, and the It becomes possible to reduce the energy difference between the singlet excitation energy level and the triplet excitation energy level. Further, it becomes possible to maintain the triplet excitation energy level of compound 134 at a high energy level.

When the TADF material is composed of one type of material, the following materials can be used, for example.

First, examples include fullerene and its derivatives, acridine derivatives such as proflavin, eosin, and the like. Other metal-containing porphyrins include magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), and the like. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF ₂ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ₂ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ₂ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ₂ (OEP)), ethioporphyrin-tin fluoride Examples include complex (SnF ₂ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ₂ OEP), and the like.

Further, as the thermally activated delayed fluorescent material composed of one kind of material, a heterocyclic compound having a π-electron-rich skeleton and a π-electron-deficient skeleton can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5- Triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4 -(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl- 9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS) , 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-3,3'-bi-9H- Carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]benzofuro [3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3' -Bi-9H-carbazole (abbreviation: mPCCzPTzn-02) and other heterocyclic compounds having one or both of a π-electron-excessive heteroaromatic ring and a π-electron-deficient heteroaromatic ring can be mentioned. Since the heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, it has high electron transport properties and hole transport properties, and is therefore preferable. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeletons, diazine skeletons (pyrimidine skeletons, pyrazine skeletons, pyridazine skeletons), and triazine skeletons are preferred because they are stable and have good reliability. In particular, a benzofuropyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuropyrazine skeleton, and a benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, at least one of the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton is stable and reliable. It is preferable to have. Note that the furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. Further, as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferable. In addition, in a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded, both the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are strong, This is particularly preferable because the difference between the singlet excited state level and the triplet excited state level becomes small. Note that instead of the π electron-deficient heteroaromatic ring, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used. Further, as the π-electron-excessive skeleton, an aromatic amine skeleton, a phenazine skeleton, etc. can be used. In addition, as the π-electron deficient skeleton, xanthene skeleton, thioxanthene skeleton, dioxide skeleton, oxadiazole skeleton, triazole skeleton, imidazole skeleton, anthraquinone skeleton, boron-containing skeleton such as phenylborane and boranethrene, benzonitrile or cyanobenzene, etc. An aromatic ring or a heteroaromatic ring having a nitrile group or a cyano group, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. can be used. In this way, a π-electron-deficient skeleton and a π-electron-excessive skeleton can be used in place of at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring.

When compound 134 does not have the function of converting triplet excitons into luminescence, the combination of compound 131 and compound 133 or compound 131 and compound 134 is preferably a combination that forms an exciplex with each other, but there is no particular limitation. . It is preferable that one has the function of transporting electrons and the other has the function of transporting holes.

Compound 131 includes zinc and aluminum metal complexes, as well as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, and bipyridine. derivatives, phenanthroline derivatives, etc. Other examples include aromatic amines and carbazole derivatives.

Further, the following hole transporting materials and electron transporting materials can be used.

As the hole-transporting material, a material having a higher hole-transporting property than that of electrons can be used, and a material having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more is preferable. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. Further, the hole transporting material may be a polymer compound.

Examples of these materials with high hole transport properties include aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4, 4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N , N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino] Examples include benzene (abbreviation: DPA3B).

In addition, specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-( 4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9 -Phenylcarbazole (abbreviation: PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-( 9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino ]-9-phenylcarbazole (abbreviation: PCzPCN1) and the like.

In addition, as carbazole derivatives, 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB) ), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5, 6-tetraphenylbenzene and the like can be used.

Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1- naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4 -Methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl) phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-biantryl, 10,10'-diphenyl-9,9'-biantryl, 10,10'-bis(2-phenylphenyl)-9,9'-biantryl, 10,10'-bis[(2 , 3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, and the like. In addition, pentacene, coronene, etc. can also be used. Thus, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more and having 14 to 42 carbon atoms.

Note that the aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2- Examples include diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino) phenyl]phenyl-N'-phenylamino}phenyl) methacrylamide] (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Polymer compounds such as Poly-TPD) can also be used.

In addition, examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD) and N,N'- Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazole-9 -yl) triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4, 4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino] Triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4 '-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-( 9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl) Amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2- [N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl) Triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)- 4'-(9-phenyl-9H-carbazol-3-yl)-triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole) -3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazole) -3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9- Phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9- Phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] -9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] -Fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-amine ( Abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N-(4 -diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl) Phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) Aromatic amine compounds such as ) can be used. Also, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis( 3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II ), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl)- Benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4- (9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp- Amine compounds such as II), carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. can be used. The substances described here mainly have a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more. However, materials other than these may be used as long as they have a higher transportability for holes than for electrons.

As the electron transporting material, a material that transports electrons higher than holes can be used, and preferably has an electron mobility of 1×10 ⁻⁶ cm ² /Vs or more. As the material that easily accepts electrons (material that has electron transport properties), π electron-deficient heteroaromatics such as nitrogen-containing heteroaromatic compounds, metal complexes, and the like can be used. Specifically, metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives. Examples include.

For example, tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq ₃ ), bis(10-hydroxybenzo[h]quinolinato) Beryllium (II) (abbreviation: BeBq ₂ ), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation) :Znq), metal complexes having a quinoline skeleton or a benzoquinoline skeleton, and the like. In addition, bis[2-(2-benzooxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), etc. Metal complexes having oxazole-based or thiazole-based ligands can also be used. Furthermore, in addition to metal complexes, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5 -(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxa diazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole( Abbreviation: TAZ), 2,2',2''-(1,3,5-benzentriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene) -4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), bathophenanthroline (abbreviation: BPhen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl Heterocyclic compounds such as -1,10-phenanthroline (abbreviation: NBPhen), bathocuproine (abbreviation: BCP), and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(9H-carbazole) -9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f, h] Quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl] Thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4 , 6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4 , 6mCzP2Pm), and 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6 Heterocyclic compounds having a triazine skeleton such as -diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) and 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) ), heterocyclic compounds having a pyridine skeleton such as 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 4,4'-bis(5-methylbenzoxazole-2- Heteroaromatic compounds such as stilbene (abbreviation: BzOs) can also be used. In addition, poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF -Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy). Molecular compounds can also be used. The substances described here mainly have an electron mobility of 1×10 ⁻⁶ cm ² /Vs or more. Note that any substance other than the above may be used as long as it has a higher transportability for electrons than for holes.

As compound 134, a combination that can form an exciplex with compound 131 is preferable. Specifically, the hole-transporting materials and electron-transporting materials shown above can be used. In this case, the emission peak of the exciplex formed by compound 131 and compound 134 overlaps with the absorption band on the longest wavelength side (lower energy side) of compound 133 (phosphorescent material having a five-membered ring skeleton). It is preferable to select Compound 131, Compound 134, and Compound 133 (phosphorescent material having a 5-membered ring skeleton). Thereby, a light emitting device with dramatically improved luminous efficiency can be obtained.

Note that the light-emitting layer 130 can also be composed of two or more layers. For example, when forming the light emitting layer 130 by laminating the first light emitting layer and the second light emitting layer in order from the hole transporting layer side, using a substance having hole transporting properties as the host material of the first light emitting layer, There is a configuration in which a substance having electron transporting properties is used as the host material of the second light emitting layer.

Further, the light-emitting layer 130 may contain a material (compound 135) other than the compound 131, the compound 132, the compound 133, and the compound 134. In that case, in order for compound 131 and compound 133 (or compound 134) to efficiently form an exciplex, it is necessary that the HOMO level of one of compound 131 and compound 133 (or compound 134) is higher than that of the material in the light-emitting layer 130. It is preferable that one of the materials has the highest HOMO level, and the other has the lowest LUMO level of the materials in the light emitting layer 130. By establishing such a correlation of energy levels, it is possible to suppress the reaction of compound 131 and compound 135 to form an exciplex.

For example, when compound 131 has a hole transport property and compound 133 (or compound 134) has an electron transport property, the HOMO level of compound 131 is higher than the HOMO level of compound 133 and the HOMO level of compound 135. It is preferable that the LUMO level of compound 133 is lower than the LUMO level of compound 131 and the LUMO level of compound 135. In this case, the LUMO level of compound 135 may be higher or lower than that of compound 131. Further, the HOMO level of compound 135 may be higher or lower than the HOMO level of compound 133.

The material (compound 135) that can be used for the light emitting layer 130 is not particularly limited, but for example, tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato) ) Aluminum (III) (abbreviation: Almq ₃ ), bis(10-hydroxybenzo[h]quinolinato) beryllium (II) (abbreviation: BeBq ₂ ), bis(2-methyl-8-quinolinato) (4-phenylphenolate) ) aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzooxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) , metal complexes such as bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4 -Oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3, 5-benzentriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 9-[4-(5-phenyl-1, Heterocyclic compounds such as 3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD) , 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB). Further, fused polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives are mentioned, and specifically, 9,10-diphenylanthracene (abbreviation: DPAnth) , N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenyl Amine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4 -(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl ] Phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene -2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9- [4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di( 2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-biantryl (abbreviation: BANT), 9, 9'-(Stilbene-3,3'-diyl) diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl) diphenanthrene (abbreviation: DPNS2), 1,3,5- Examples include tri(1-pyrenyl)benzene (abbreviation: TPB3). Further, from among these and known substances, one or more substances having an energy gap larger than that of the compounds 131 and 132 may be selected and used.

≪Pair of electrodes≫
The electrode 101 and the electrode 102 have a function of injecting holes and electrons into the light emitting layer 130. The electrode 101 and the electrode 102 can be formed using a metal, an alloy, a conductive compound, a mixture thereof, a laminate, or the like. Aluminum (Al) is a typical example of the metal, but other metals include transition metals such as silver (Ag), tungsten, chromium, molybdenum, copper, and titanium, alkali metals such as lithium (Li) and cesium, calcium, and magnesium (Mg). ) can be used. A rare earth metal such as ytterbium (Yb) may be used as the transition metal. As the alloy, an alloy containing the above-mentioned metals can be used, and examples thereof include MgAg and AlLi. Examples of conductive compounds include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (abbreviation: ITSO), indium zinc oxide, tungsten and zinc. Examples include metal oxides such as indium oxide containing . Inorganic carbon-based materials such as graphene may be used as the conductive compound. As described above, one or both of the electrode 101 and the electrode 102 may be formed by laminating a plurality of these materials.

Further, the light emitted from the light emitting layer 130 is extracted through one or both of the electrodes 101 and 102. Therefore, at least one of the electrode 101 and the electrode 102 has a function of transmitting visible light. The conductive material having the function of transmitting light has a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 ^-2 Ωcm. The following conductive materials may be mentioned. Further, the electrode for extracting light may be formed of a conductive material having a function of transmitting light and a function of reflecting light. The conductive material may have a visible light reflectance of 20% or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1×10 ^-2 Ωcm or less. Can be mentioned. When using a material with low light transmittance such as metal or alloy for the electrode that extracts light, the electrodes 101 and 102 should be thick enough to transmit visible light (for example, 1 nm to 10 nm thick). One or both may be formed.

In this specification and the like, the electrode having the function of transmitting light may be made of a material having the function of transmitting visible light and having conductivity, such as the above-mentioned ITO. In addition to the oxide conductor layer, an oxide semiconductor layer or an organic conductor layer containing an organic substance is included. Examples of the organic conductor layer containing an organic substance include a layer containing a composite material made by mixing an organic compound and an electron donor, and a composite material made by mixing an organic compound and an electron acceptor. Examples include a layer containing. Further, the resistivity of the transparent conductive layer is preferably 1×10 ⁵ Ω·cm or less, more preferably 1×10 ⁴ Ω·cm or less.

The electrode 101 and the electrode 102 may be formed by a sputtering method, a vapor deposition method, a printing method, a coating method, an MBE (Molecular Beam Epitaxy) method, a CVD method, a pulsed laser deposition method, an ALD (Atomic Layer Deposition) method, etc. It can be used as appropriate.

≪Hole injection layer≫
The hole injection layer 111 has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and is made of, for example, a transition metal oxide, a phthalocyanine derivative, or an aromatic material. Formed by group amines, etc. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, and the like. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, with typical examples being self-doped polythiophenes such as poly(ethylenedioxythiophene)/poly(styrene sulfonic acid).

As the hole injection layer 111, a layer including a composite material of a hole transporting material and a material exhibiting electron-accepting properties can also be used. Alternatively, a stack of a layer containing an electron-accepting material and a layer containing a hole-transporting material may be used. Charges can be exchanged between these materials in a steady state or in the presence of an electric field. Examples of materials exhibiting electron-accepting properties include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ), chloranil, 2,3,6,7,10,11 -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: Examples include compounds having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) such as F6-TCNNQ). In particular, a compound such as HAT-CN in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms is thermally stable and is therefore preferred. Furthermore, [3] radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferable because they have very high electron-accepting properties, and specifically, α, α', α''- 1,2,3-cyclopropane triylidentris [4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidentris [2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidentris [2,3,4, 5,6-pentafluorobenzeneacetonitrile] and the like. Also, transition metal oxides, such as oxides of Group 4 to Group 8 metals, can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc. are used. Among them, molybdenum oxide is preferred because it is stable even in the atmosphere, has low hygroscopicity, and is easy to handle.

As the hole-transporting material, a material having a higher hole-transporting property than electrons can be used, and a material having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more is preferable. Specifically, aromatic amines and carbazole derivatives mentioned as hole transporting materials that can be used in the light emitting layer 130 can be used. Furthermore, aromatic hydrocarbons, stilbene derivatives, and the like can be used. Further, the hole transporting material may be a polymer compound.

Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl) Anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9, 10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl) -1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl] Anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9, 9'-Biantryl, 10,10'-diphenyl-9,9'-Biantryl, 10,10'-bis(2-phenylphenyl)-9,9'-Biantryl, 10,10'-bis[(2,3 , 4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, and the like. In addition, pentacene, coronene, etc. can also be used. As described above, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more and having 14 to 42 carbon atoms.

Note that the aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2- Examples include diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino) phenyl]phenyl-N'-phenylamino}phenyl) methacrylamide] (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Polymer compounds such as Poly-TPD) can also be used.

≪Hole transport layer≫
The hole transport layer 112 is a layer containing a hole transporting material, and the materials exemplified as the material for the hole injection layer 111 can be used. Since the hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the light emitting layer 130, it may have a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111. preferable.

As the above-mentioned hole transporting material, the materials exemplified as the material of the hole injection layer 111 can be used. Further, it is preferable that the material has a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more. However, any material other than these may be used as long as it has a higher transportability for holes than for electrons. Note that the layer containing a substance with high hole transport properties may not only be a single layer, but may also be a stack of two or more layers made of the above substance.

≪Electron transport layer≫
The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (electrode 101 or electrode 102) via the electron injection layer 119 to the light emitting layer 130. As the electron transporting material, a material that transports electrons higher than holes can be used, and preferably has an electron mobility of 1×10 ⁻⁶ cm ² /Vs or more. As the compound that easily accepts electrons (material having electron transport properties), π electron-deficient heteroaromatics such as nitrogen-containing heteroaromatic compounds, metal complexes, and the like can be used. Specifically, metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands mentioned as electron-transporting materials that can be used in the light-emitting layer 130 can be mentioned. Further examples include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives. Further, it is preferable that the material has an electron mobility of 1×10 ⁻⁶ cm ² /Vs or more. Note that any material other than those mentioned above may be used as the electron transport layer, as long as it has a higher transport property for electrons than for holes. Further, the electron transport layer 118 is not limited to a single layer, and may be a stack of two or more layers made of the above substances.

Further, a layer for controlling movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 130. The layer that controls the movement of electron carriers is a layer made by adding a small amount of a substance with high electron trapping properties to the material with high electron transport properties as described above, and controls the carrier balance by suppressing the movement of electron carriers. It becomes possible to do so. Such a configuration is highly effective in suppressing problems caused by electrons penetrating the light emitting layer (for example, a reduction in device life).

≪Electron injection layer≫
The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and is made of, for example, a Group 1 metal, a Group 2 metal, or their oxides, halides, carbonates, etc. can be used. Furthermore, a composite material of the electron transporting material shown above and a material exhibiting electron donating properties can also be used. Examples of materials exhibiting electron donating properties include Group 1 metals, Group 2 metals, and oxides thereof. Specifically, alkali metals and alkaline earths such as lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), lithium oxide (LiO _x ), etc. Similar metals or compounds thereof can be used. Also, rare earth metal compounds such as erbium fluoride (ErF ₃ ) can be used. Further, electride may be used for the electron injection layer 119. Examples of the electride include a substance obtained by adding a high concentration of electrons to a mixed oxide of calcium and aluminum. Further, a substance that can be used in the electron transport layer 118 may be used for the electron injection layer 119.

Further, a composite material formed by mixing an organic compound and an electron donor may be used for the electron injection layer 119. Such a composite material has excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons, and specifically, for example, a material (such as a metal complex or a heteroaromatic compound) constituting the electron transport layer 118 described above is used as the organic compound. Can be used. The electron donor may be any substance that exhibits electron-donating properties to organic compounds. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, and examples include lithium, cesium, magnesium, calcium, erbium, and ytterbium. Moreover, alkali metal oxides and alkaline earth metal oxides are preferable, and examples thereof include lithium oxide, calcium oxide, barium oxide, and the like. Additionally, Lewis bases such as magnesium oxide can also be used. Moreover, organic compounds such as tetrathiafulvalene (abbreviation: TTF) can also be used.

The above-mentioned light-emitting layer, hole-injection layer, hole-transport layer, electron-transport layer, and electron-injection layer can be formed by a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, a nozzle printing method, It can be formed by a method such as gravure printing. In addition to the above-mentioned materials, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymer, etc.) may also be used.

Note that as the quantum dots, colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. may be used. Alternatively, quantum dots containing element groups of groups 2 and 16, groups 13 and 15, groups 13 and 17, groups 11 and 17, or groups 14 and 15 may be used. Or cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As ), aluminum (Al), or other elements may be used.

Liquid media used in the wet process include, for example, ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, and aromatic carbons such as toluene, xylene, mesitylene, and cyclohexylbenzene. Hydrogens, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can be used.

In addition, examples of polymer compounds that can be used in the light-emitting layer include poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (abbreviation: MEH-PPV), poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (abbreviation: MEH-PPV), , 5-dioctyl-1,4-phenylene vinylene), poly(9,9-di-n-octylfluorenyl-2,7-diyl) (abbreviation: PF8), poly[ (9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (abbreviation: F8BT), poly[( 9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviation F8T2), poly[(9,9- Dioctyl-2,7-divinylenefluorenylene)-alt-(9,10-anthracene)], poly[(9,9-dihexylfluorene-2,7-diyl)-alt-(2,5-dimethyl- 1,4-phenylene)], polyalkylthiophene (PAT) derivatives such as poly(3-hexylthiophene-2,5-diyl) (abbreviation: P3HT), and polyphenylene derivatives. In addition, these polymer compounds, poly(N-vinylcarbazole) (abbreviation: PVK), poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTAA) or the like may be doped with a light-emitting compound and used for the light-emitting layer. As the luminescent compound, the luminescent compounds listed above can be used.

≪Substrate≫
Further, a light-emitting device according to one embodiment of the present invention may be manufactured over a substrate made of glass, plastic, or the like. As for the order in which they are formed on the substrate, they may be stacked sequentially from the electrode 101 side, or may be stacked sequentially from the electrode 102 side.

Note that as a substrate on which a light-emitting device according to one embodiment of the present invention can be formed, for example, glass, quartz, plastic, or the like can be used. Alternatively, a flexible substrate may be used. The flexible substrate refers to a bendable (flexible) substrate, and includes, for example, a plastic substrate made of polycarbonate or polyarylate. Further, a film, an inorganic vapor-deposited film, etc. can also be used. Note that materials other than these may be used as long as they function as supports in the manufacturing process of light emitting devices and optical devices. Alternatively, any material may be used as long as it has the function of protecting the light emitting device and the optical device.

For example, in this specification and the like, light emitting devices can be formed using various substrates. The type of substrate is not particularly limited. Examples of such substrates include semiconductor substrates (e.g. single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates with stainless steel foil, and tungsten substrates. , a substrate with tungsten foil, a flexible substrate, a laminated film, a cellulose nanofiber (CNF) or paper containing fibrous material, or a base film. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or soda lime glass. Examples of flexible substrates, bonded films, base films, etc. include the following. For example, there are plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is resin such as acrylic. Alternatively, examples include polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Alternatively, examples include polyamide, polyimide, aramid, epoxy, inorganic vapor-deposited film, and paper.

Alternatively, a flexible substrate may be used as the substrate, and the light emitting device may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light emitting device. The release layer can be used to separate from the substrate and transfer it to another substrate after a light emitting device is partially or completely completed thereon. In this case, the light emitting device can be transferred to a substrate with poor heat resistance or a flexible substrate. Note that the above-mentioned peeling layer may have, for example, a laminated structure of an inorganic film of a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate.

That is, a light emitting device may be formed using a certain substrate, and then the light emitting device may be transferred to another substrate, and the light emitting device may be placed on the other substrate. In addition to the above-mentioned substrates, examples of substrates on which light-emitting devices are transferred include cellophane substrates, stone substrates, wood substrates, cloth substrates (natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), Examples include recycled fibers (including acetate, cupro, rayon, recycled polyester, etc.), leather substrates, and rubber substrates. By using these substrates, a light-emitting device that is hard to break, a light-emitting device with high heat resistance, a light-emitting device that is lightweight, or a light-emitting device that is thinner can be made.

Further, for example, a field effect transistor (FET) may be formed on the above-described substrate, and the light emitting device 150 may be manufactured on an electrode electrically connected to the FET. As a result, an active matrix display device in which driving of a light emitting device is controlled using FETs can be manufactured.

As described above, the structure shown in this embodiment can be used in combination with other embodiments as appropriate.

(Embodiment 2)
In this embodiment, an example of a method for synthesizing an organic compound that is preferably used in the light-emitting device of one embodiment of the present invention will be described using organic compounds represented by general formulas (G1) and (G2) as examples.

<Method for synthesizing organic compound represented by general formula (G1)>
The organic compound represented by the above general formula (G1) can be synthesized by synthetic methods applying various reactions. For example, it can be synthesized by synthetic schemes (S-1) and (S-2) shown below. A diamine compound (compound 4) is obtained by coupling compound 1, arylamine (compound 2), and arylamine (compound 3).

Subsequently, by coupling the diamine compound (compound 4), the aryl halide (compound 5), and the aryl halide (compound 6), an organic compound represented by the above general formula (G1) is obtained. I can do it.

In addition, in the above synthetic schemes (S-1) and (S-2), A is a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms. , Ar ¹ to Ar ⁴ each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms, and X ¹ to X ⁸ each independently represent an alkyl group having 3 to 10 carbon atoms. , a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. Examples of the condensed ring or condensed heteroaromatic ring include chrysene, phenanthrene, stilbene, acridone, phenoxazine, and phenothiazine. Particularly preferred are anthracene, pyrene, coumarin, quinacridone, perylene, tetracene, and naphthobisbenzofuran.

In addition, in the above synthetic schemes (S-1) and (S-2), when performing the Buchwald-Hartwig reaction using a palladium catalyst, X ¹⁰ to X ¹³ represent a halogen group or a triflate group, and the halogen is Iodine or bromine or chlorine are preferred. In this reaction, palladium compounds such as bis(dibenzylideneacetone)palladium(0) and palladium(II) acetate are combined with tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1- Ligands such as (adamantyl)-n-butylphosphine and 2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl can be used. Furthermore, organic bases such as sodium tert-butoxide, inorganic bases such as potassium carbonate, cesium carbonate, sodium carbonate, etc. can be used. Further, as a solvent, toluene, xylene, mesitylene, benzene, tetrahydrofuran, dioxane, etc. can be used. Note that the reagents that can be used in the reaction are not limited to these reagents.

Furthermore, the reactions performed in the above synthetic schemes (S-1) and (S-2) are not limited to Buchwald-Hartwig reactions, but include Migita-Kosugi-Still coupling reactions using organotin compounds, Grignard reagents, etc. A coupling reaction using copper, an Ullmann reaction using copper or a copper compound, etc. can be used.

In the above synthesis scheme (S-1), when Compound 2 and Compound 3 have different structures, Compound 1 and Compound 2 are first reacted to form a coupled product, and the resulting coupled product is combined with Compound 3. It is preferable to react with. In addition, when compound 1 is reacted stepwise with compound 2 and compound 3, compound 1 is preferably a dihalogen compound, and X ¹⁰ and X ¹¹ are selectively reacted one by one using different halogens. It is preferable to carry out the amination reaction separately.

Furthermore, in the synthesis scheme (S-2), when Compound 5 and Compound 6 have different structures, Compound 4 and Compound 5 are first reacted to obtain a coupled product, and then the resulting coupled product is It is preferable to react with compound 6.

<Method for synthesizing organic compound represented by general formula (G2)>
The organic compound of one embodiment of the present invention represented by general formula (G2) can be synthesized using any organic reaction. As examples, two methods are shown below.

The first method consists of the following synthesis schemes (S-3) to (S-8). In the first step, an amine compound (compound 9) is obtained by a condensation reaction between an aniline compound (compound 7) and a 1,4-cyclohexadiene-1,4-dicarboxylic acid compound (compound 8). This process is shown in Scheme (S-3). However, it is possible to condense two aniline compounds (compound 7) having the same substituent in one step, and when introducing an amino group having the same substituent, two equivalents of the aniline compound (compound 7) can be condensed. In addition, it is preferable to carry out the same reaction. In that case, even if the carbonyl group of compound 8 has no reaction selectivity, a single target product can be obtained.

Next, a 1,4-cyclohexadiene compound (compound 11) can be obtained by subjecting the amine compound (compound 9) and the aniline derivative (compound 10) to a condensation reaction. The process for obtaining Compound 11 is shown in Scheme (S-4).

Next, a terephthalic acid compound (compound 12) can be obtained by oxidizing the 1,4-cyclohexadiene compound (compound 11) in air. The process for obtaining Compound 12 is shown in Scheme (S-5).

Next, a quinacridone compound (compound 13) can be obtained by ring condensing the terephthalic acid compound (compound 12) using an acid. The process for obtaining Compound 13 is shown in Scheme (S-6).

Next, a quinacridone compound (compound 15) can be obtained by coupling the quinacridone compound (compound 13) and an aryl halide (compound 14). The process for obtaining Compound 15 is shown in Scheme (S-7). However, it is possible to couple two aryl halides (compound 8) having the same substituent in one step, and when introducing an amino group having the same substituent, two equivalents of aryl halide (compound 8) can be coupled in one step. It is preferable to carry out the same reaction by adding 14). In that case, a single target product can be obtained even if the amino group of compound 14 has no reaction selectivity.

Next, by coupling the quinacridone compound (compound 15) and the aryl halide (compound 16), an organic compound represented by the above general formula (G2) can be obtained. This process is shown in Scheme (S-8).

The second method consists of the following synthesis schemes (S-3) to (S-5), (S-9), (S-10), and (S-11). The explanations for (S-3) to (S-5) are as above. A diamine compound (compound 17) can be obtained by coupling a terephthalic acid compound (compound 12) and an aryl halide (compound 14). The process for obtaining Compound 17 is shown in Scheme (S-9). However, if two molecules of an aryl halide having the same substituent can be coupled in one step, and an amino group having the same substituent is to be introduced, two equivalents of the aryl halide (compound 14) should be added. It is preferable to carry out the same reaction. In that case, a single target product can be obtained even if the amino group of compound 12 has no reaction selectivity.

Next, a diamine compound (compound 18) can be obtained by coupling the diamine compound (compound 17) and the aryl halide (compound 16). The process for obtaining Compound 18 is shown in Scheme (S-10).

Finally, by condensing the diamine compound (compound 18) with an acid, an organic compound represented by the above general formula (G2) can be obtained. This step is shown in Scheme (S-11). However, during the ring condensation reaction, hydrogen at the ortho position of Ar ⁵ or Ar ⁶ may react, and an isomer of the organic compound represented by the above general formula (G2) may be generated.

In scheme (S-11), by using a diamine compound (compound 18) having a symmetrical structure, it is possible to synthesize an organic compound represented by the above general formula (G2).

In synthetic schemes (S-3) to (S-6) and (S-9) to (S-11), Al ¹ represents an alkyl group such as a methyl group.

In synthetic schemes (S-7) to (S-10), Y ¹ and Y ² represent chlorine, bromine, iodine, or triflate groups.

In synthetic schemes (S-7) to (S-10), it is preferable to perform the Ullmann reaction because the reaction can proceed at high temperatures and the target compound can be obtained in a relatively high yield. Reagents that can be used in the reaction include copper or copper compounds, and bases include inorganic bases such as potassium carbonate and sodium hydride. In the reaction, solvents that can be used include 2,2,6,6-tetramethyl-3,5-heptanedione, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene, xylene, benzene, etc. In the Ullmann reaction, the target product can be obtained in a shorter time and in a higher yield when the reaction temperature is 100°C or higher, so 2,2,6,6-tetramethyl-3,5-heptanedione, DMPU, which has a high boiling point, , xylene is preferably used. Moreover, since the reaction temperature is more preferably a high temperature of 150° C. or higher, DMPU is more preferably used. Reagents that can be used in the reaction are not limited to the above-mentioned reagents.

In synthetic schemes (S-7) to (S-10), a Buchwald-Hartwig reaction using a palladium catalyst can be performed, and in this reaction, bis(dibenzylideneacetone)palladium(0), palladium acetate(II) ), [1,1-bis(diphenylphosphino)ferrocene]palladium(II) dichloride, tetrakis(triphenylphosphine)palladium(0), allylpalladium(II) chloride (dimer), and palladium compounds such as -butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, tri(orthotolyl)phosphine, A ligand such as (S)-(6,6'-dimethoxybiphenyl-2,2'-diyl)bis(diisopropylphosphine) (abbreviation: cBRIDP (registered trademark)) can be used. In this reaction, organic bases such as sodium tert-butoxide, inorganic bases such as potassium carbonate, cesium carbonate, sodium carbonate, etc. can be used. In this reaction, toluene, xylene, benzene, tetrahydrofuran, dioxane, etc. can be used as a solvent. Reagents that can be used in the reaction are not limited to the above reagents.

Furthermore, the method for synthesizing the organic compound represented by the general formula (G2) of the present invention is not limited to the synthetic schemes (S-1) to (S-11).

Specific examples of R ¹ to R ¹⁰ substituted on the quinacridone skeleton include n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group. group, trimethylsilyl group, triethylsilyl group, tolbutylsilyl group, etc.

Specific examples of Ar ⁵ substituted with X ⁹ and X ¹⁰ and Ar ⁶ substituted with X ¹¹ and X ¹² include 2-isopropylphenyl group, 2-butylphenyl group, 2-isobutylphenyl group, 2-tert- Butylphenyl group, 2-isopropylphenyl group, 2-butylphenyl group, 3-propylphenyl group, 3-isobutylphenyl group, 3-tert-butylphenyl group, 4-propylphenyl group, 4-isopropylphenyl group, 4- Butylphenyl group, 4-isobutylphenyl group, 4-tert-butylphenyl group, 3,5-dipropylphenyl group, 3,5-di-isopropylphenyl group, 3,5-dibutylphenyl group, 3,5-dipropylphenyl group, -isobutylphenyl group, (3,5-di-tert-butyl)phenyl group, 1,3-dipropylphenyl group, 1,3-di-isopropylphenyl group, 1,3-dibutylphenyl group, 1,3- Di-isobutylphenyl group, (1,3-di-tert-butyl) phenyl group, 1,3,5-triisopropylphenyl group, (1,3,5-tri-tert-butyl) phenyl group, 4-cyclohexyl Examples include phenyl group.

Although the method for synthesizing organic compounds represented by general formula (G1) and general formula (G2), which is one embodiment of the present invention, has been described above, the present invention is not limited thereto, and other synthetic methods may be used. It may be synthesized by any method.

(Embodiment 3)
In this embodiment, a light-emitting device having a structure different from that of the light-emitting device shown in Embodiment 1 will be described below with reference to FIG. In addition, in FIG. 6, parts having the same functions as the symbols shown in FIG. 1A are given the same hatch pattern, and the symbols may be omitted. In addition, parts having similar functions are given the same reference numerals, and detailed explanation thereof may be omitted.

<Configuration example 2 of light emitting device>
FIG. 6 is a schematic cross-sectional view of the light emitting device 250.

A light emitting device 250 shown in FIG. 6 includes a plurality of light emitting units (a light emitting unit 106 and a light emitting unit 108) between a pair of electrodes (an electrode 101 and an electrode 102). It is preferable that any one of the plurality of light emitting units has the same configuration as the EL layer 100 shown in FIG. 1A. That is, it is preferable that the light-emitting device 150 shown in FIG. 1A has one light-emitting unit, and the light-emitting device 250 has a plurality of light-emitting units. Note that in the light emitting device 250, the following description will be made assuming that the electrode 101 functions as an anode and the electrode 102 functions as a cathode, but the configuration of the light emitting device 250 may be reversed.

Furthermore, in the light emitting device 250 shown in FIG. 6, the light emitting unit 106 and the light emitting unit 108 are stacked, and the charge generation layer 115 is provided between the light emitting unit 106 and the light emitting unit 108. Note that the light emitting unit 106 and the light emitting unit 108 may have the same configuration or different configurations. For example, it is preferable to use the same configuration as the EL layer 100 for the light emitting unit 108.

Further, the light emitting device 250 includes a light emitting layer 120 and a light emitting layer 170. In addition to the light emitting layer 120, the light emitting unit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. In addition to the light emitting layer 170, the light emitting unit 108 includes a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

In the light-emitting device 250, the compound according to one embodiment of the present invention may be included in any layer of the light-emitting unit 106 or the light-emitting unit 108. Note that the layer containing the compound is preferably the light-emitting layer 120 or the light-emitting layer 170.

The charge generation layer 115 may have a structure in which an acceptor substance, which is an electron acceptor, is added to a hole-transporting material, or a donor substance, which is an electron donor, is added to an electron-transporting material. It's okay. Further, both of these structures may be stacked.

When charge generation layer 115 includes a composite material of an organic compound and an acceptor substance, a composite material that can be used for hole injection layer 111 shown in Embodiment 1 may be used as the composite material. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and high molecular compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that it is preferable to use an organic compound having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more. However, materials other than these may be used as long as they have a higher transportability for holes than for electrons. A composite material of an organic compound and an acceptor substance has excellent carrier injection properties and carrier transport properties, and thus can realize low voltage drive and low current drive. Note that when the anode side surface of the light emitting unit is in contact with the charge generation layer 115, the charge generation layer 115 can also play the role of a hole injection layer or a hole transport layer of the light emitting unit. The unit may be configured without a hole injection layer or a hole transport layer. Alternatively, if the cathode side surface of the light emitting unit is in contact with the charge generation layer 115, the charge generation layer 115 can also play the role of an electron injection layer or an electron transport layer of the light emitting unit. may have a structure in which no electron injection layer or electron transport layer is provided.

Note that the charge generation layer 115 may be formed as a laminated structure in which a layer containing a composite material of an organic compound and an acceptor substance is combined with a layer composed of another material. For example, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance, and a layer containing a compound selected from electron donating substances and a compound with high electron transport properties. Alternatively, a layer containing a composite material of an organic compound and an acceptor substance and a layer containing a transparent conductive film may be formed in combination.

Note that the charge generation layer 115 sandwiched between the light emitting unit 106 and the light emitting unit 108 injects electrons into one light emitting unit and injects holes into the other light emitting unit when a voltage is applied to the electrode 101 and the electrode 102. It is fine as long as it injects. For example, in FIG. 6, when a voltage is applied such that the potential of the electrode 101 is higher than the potential of the electrode 102, the charge generation layer 115 injects electrons into the light emitting unit 106 and holes into the light emitting unit 108. inject.

Note that, from the viewpoint of light extraction efficiency, the charge generation layer 115 preferably has a property of transmitting visible light (specifically, the transmittance of visible light to the charge generation layer 115 is 40% or more). Further, the charge generation layer 115 functions even if the conductivity is lower than that of the pair of electrodes (electrode 101 and electrode 102).

By forming the charge generation layer 115 using the above-mentioned material, it is possible to suppress an increase in driving voltage when light emitting layers are stacked.

Further, in FIG. 6, a light emitting device having two light emitting units has been described, but the present invention can be similarly applied to a light emitting device in which three or more light emitting units are stacked. As shown in the light-emitting device 250, by arranging a plurality of light-emitting units separated by a charge generation layer between a pair of electrodes, it is possible to emit high-intensity light while keeping the current density low, and the light-emitting device has a longer life. can be realized. Furthermore, a light emitting device with low power consumption can be realized.

Note that in each of the above configurations, the emission colors exhibited by the guest materials used in the light-emitting unit 106 and the light-emitting unit 108 may be the same or different. When the light-emitting unit 106 and the light-emitting unit 108 each include a guest material having the function of emitting light of the same color, the light-emitting device 250 becomes a light-emitting device that exhibits high luminance with a small current value, which is preferable. Further, in the case where the light emitting unit 106 and the light emitting unit 108 include a guest material having a function of emitting light of different colors, the light emitting device 250 becomes a light emitting device that emits multicolor light, which is preferable. In this case, by using a plurality of light emitting materials with different emission wavelengths in either or both of the light emitting layer 120 and the light emitting layer 170, the light emission spectrum exhibited by the light emitting device 250 is a combination of light emissions having different emission peaks. Therefore, the emission spectrum has at least two maximum values.

The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light from the light emitting layer 120 and the light emitting layer 170 complementary colors to each other. In particular, it is preferable to select the guest material so as to emit white light with high color rendering properties, or emit light having at least red, green, and blue.

It is preferable to use the structure of the light-emitting layer 130 described in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. With this configuration, a light emitting device with good luminous efficiency and reliability can be obtained. The guest material included in the light emitting layer 130 is a fluorescent material. Therefore, by using the structure of the light-emitting layer 130 described in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting device with high efficiency and high reliability can be obtained.

Furthermore, in the case of a light-emitting device in which three or more light-emitting units are stacked, the emission colors exhibited by the guest materials used in each light-emitting unit may be the same or different. When having a plurality of light emitting units that emit light of the same color, the plurality of light emitting units can emit high intensity light with a small current value. Such a configuration can be suitably used for adjusting the color of emitted light. This is particularly suitable when using guest materials that have different luminous efficiencies and emit different luminescent colors. For example, in the case of having a three-layer light-emitting unit, two layers of light-emitting units each having a fluorescent material of the same color and one layer having a phosphorescent material exhibiting an emission color different from that of the fluorescent material, The intensity of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emitted color can be adjusted by the number of light emitting units.

In the case of such a light emitting device having two layers of fluorescent light emitting units and one layer of phosphorescent light emitting units, a light emitting device containing two layers of light emitting units containing a blue fluorescent material and one layer of light emitting units containing a yellow phosphorescent material, A light emitting device having two layers of light emitting units containing a blue fluorescent material and one layer of light emitting units containing a red phosphorescent material and a green phosphorescent material, or two layers of light emitting units containing a blue fluorescent material and a red phosphorescent material A light emitting device having one layer of a light emitting unit containing a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. In this way, the light-emitting device of one embodiment of the present invention can be appropriately combined with a phosphorescent light-emitting layer.

Furthermore, in the above-described light-emitting device having two layers of fluorescent light-emitting units and one layer of phosphorescent light-emitting units, it is also possible to replace the phosphorescent light-emitting unit with a light-emitting unit having the structure of the light-emitting layer 130 described in Embodiment 1 above. . This is because by using the structure of the light emitting layer 130 described in Embodiment 1, a fluorescent light emitting layer having the same luminous efficiency as a phosphorescent light emitting layer can be realized.

Alternatively, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and each divided layer may contain a different light-emitting material. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, when a first light emitting layer and a second light emitting layer are laminated in order from the hole transporting layer side to form a light emitting layer, a material having a hole transporting property is used as the host material of the first light emitting layer, There is a configuration in which a material having electron transporting properties is used as the host material of the second light emitting layer. In this case, the luminescent materials of the first luminescent layer and the second luminescent layer may be the same material or different materials, and even if they have the function of emitting light of the same color, It may be a material that has the function of emitting light of different colors. With a configuration including a plurality of light emitting materials having the function of emitting light of different colors, it is also possible to obtain white light emitted with high color rendering properties consisting of three primary colors or four or more emitted colors.

Note that as a guest material for the light emitting layer of the phosphorescent unit described in Embodiment 3, for example, the following phosphorescent material can be used.

Examples of the phosphorescent material having an emission peak in blue or green include tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole -3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp) ₃ ), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium (III) (abbreviation: Ir(Mptz) ₃ ), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir( iPrptz-3b) ₃ ), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPr5btz) ₃ ), Organometallic iridium complexes having a 4H-triazole skeleton such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(Mptz1-mp) ₃ ), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me) ₃ ), etc. organometallic iridium complexes having a 1H-triazole skeleton, fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi) ₃ ), An imidazole skeleton such as tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me) ₃ ) Organometallic iridium complexes containing bis[2-(4',6'-difluorophenyl)pyridinato-N,C ^2' ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2- (4',6'-difluorophenyl)pyridinato-N,C ^2' ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato- N,C ^2' }iridium(III) picolinate (abbreviation: Ir(CF ₃ ppy) ₂ (pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ^2' ]iridium ( III) An organometallic iridium complex having a phenylpyridine derivative having an electron-withdrawing group such as acetylacetonate (abbreviation: FIr (acac)) as a ligand can be mentioned. Among the above-mentioned organometallic iridium complexes having nitrogen-containing five-membered heterocyclic skeletons such as 4H-triazole skeleton, 1H-triazole skeleton, and imidazole skeleton have high triplet excitation energy and have low reliability and luminous efficiency. It is particularly preferred because it is excellent. In addition, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (abbreviation: PtOEP) and tris[1-(2-thenoyl) Rare earth metal complexes such as -3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: Eu(TTA) ₃ (Phen)) can also be used.

In addition, examples of substances having an emission peak in green or yellow include tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm) ₃ ), tris(4-t-butyl -6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm) ₃ ), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm) ) ₂ (acac)), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm) ₂ (acac)), (acetylacetonato)bis [4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm) ₂ (acac)), (acetylacetonato)bis[5-methyl-6-(2-methyl) phenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm) ₂ (acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6- dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(dmppm-dmp) ₂ (acac)), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium Organometallic iridium complexes having a pyrimidine skeleton such as (III) (abbreviation: Ir(dppm) ₂ (acac)) and (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium ( III) (abbreviation: Ir(mppr-Me) ₂ (acac)), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr- Organometallic iridium complexes having a pyrazine skeleton such as iPr) ₂ (acac)), tris(2-phenylpyridinato-N,C ^2' )iridium(III) (abbreviation: Ir(ppy) ₃ ), bis (2-phenylpyridinato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: Ir(ppy) ₂ (acac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate ( Abbreviation: Ir(bzq) ₂ (acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq) ₃ ), tris(2-phenylquinolinato-N,C ^2' )iridium ( III) (abbreviation: Ir(pq) ₃ ), pyridine skeleton such as bis(2-phenylquinolinato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: Ir(pq) ₂ (acac)) Organometallic iridium complexes having , bis(2,4-diphenyl-1,3-oxazolato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: Ir(dpo) ₂ (acac)), bis{ 2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C ^2' }iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph) ₂ (acac)), bis(2-phenyl) In addition to organometallic iridium complexes such as benzothiazolate-N,C ^2' ) iridium (III) acetylacetonate (abbreviation: Ir(bt) ₂ (acac)), tris(acetylacetonato) (monophenanthroline) terbium ( III) (abbreviation: Tb(acac) ₃ (Phen)). Among the above-mentioned, organometallic iridium complexes having a pyrimidine skeleton are particularly preferable because they have outstanding reliability and luminous efficiency.

Further, as a substance having an emission peak in yellow or red, for example, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm) ₂ ( dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm) ₂ (dpm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) Organometallic iridium complexes having a pyrimidine skeleton such as (naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm) ₂ (dpm)), and (acetylacetonato) Bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr) ₂ (acac)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmet) (abbreviation: Ir(tppr) ₂ (dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)) Organometallic iridium complexes having a pyrazine skeleton such as ₂ (acac)), tris(1-phenylisoquinolinato-N,C ^2' )iridium(III) (abbreviation: Ir(piq) ₃ ), bis(1 In addition to organometallic iridium complexes having a pyridine skeleton such as -phenylisoquinolinato-N,C ^2' ) iridium (III) acetylacetonate (abbreviation: Ir(piq) ₂ (acac)), 2,3,7 , 8,12,13,17,18-octaethyl-21H,23H-porphyrin Platinum complexes such as platinum (II) (abbreviation: PtOEP) and tris(1,3-diphenyl-1,3-propanedionato) (monophenanthroline) europium (III) (abbreviation: Eu(DBM) ₃ (Phen)), tris[1-(2-tenoyl)-3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) Examples include rare earth metal complexes such as (abbreviation: Eu(TTA) ₃ (Phen)). Among the above-mentioned, organometallic iridium complexes having a pyrimidine skeleton are particularly preferable because they have outstanding reliability and luminous efficiency. Furthermore, an organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

Further, as the host material of the phosphorescent unit, the above-mentioned hole transporting material and/or electron transporting material can be used.

Furthermore, a structure other than the structure of the light emitting layer 130 shown in Embodiment 1 can be used in the above-described fluorescent light emitting unit. There is no particular limitation on the guest material used in the fluorescence emitting unit, but examples of fluorescent compounds include anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, and phenyl derivatives. Sazine derivatives, phenothiazine derivatives, etc. are preferable, and for example, the following substances can be used.

Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl) -9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9) -yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene) -9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N '-Bis(4-tert-butylphenyl)-pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl) ) phenyl]-N,N'-diphenyl-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl) ) phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenyl Amine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N- [4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP) , 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butyl anthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4 -(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N ',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyl Dibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole- 3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation :2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis( 1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1' -biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9 -Amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butyl) phenyl)-6,12-diphenyltetracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2- (2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2 -(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N, N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl ) acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2, 3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl -6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran-4 -ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM ), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine-9 -yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd: 1',2',3'-lm]perylene (abbreviation: DBP), and the like.

Further, as the host material of the fluorescence emitting unit, the above-mentioned hole transporting material and/or electron transporting material can be used. Note that this embodiment can be combined with other embodiments as appropriate.

(Embodiment 4)
In this embodiment, a light-emitting device using the light-emitting device described in Embodiment 1 and Embodiment 3 will be described with reference to FIGS. 7A and 7B.

7A is a top view showing the light emitting device, and FIG. 7B is a sectional view taken along AB and CD in FIG. 7A. This light-emitting device includes a drive circuit section (source-side drive circuit) 601, a pixel section 602, and a drive circuit section (gate-side drive circuit) 603 shown by dotted lines to control light emission of the light-emitting device. Further, 604 is a sealing substrate, 625 is a drying material, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

Note that the routing wiring 608 is a wiring for transmitting signals input to the source side drive circuit 601 and the gate side drive circuit 603, and is used to transmit video signals, clock signals, Receives start signals, reset signals, etc. Although only the FPC is illustrated here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device main body but also a state in which an FPC or PWB is attached to the light-emitting device.

Next, the cross-sectional structure of the light emitting device will be explained using FIG. 7B. Here, a source side drive circuit 601, which is a drive circuit section, and one pixel in a pixel section 602 are shown.

Note that the source side drive circuit 601 is a CMOS circuit formed by combining an n-channel type TFT 623 and a p-channel type TFT 624. Furthermore, the drive circuit may be formed of various CMOS circuits, PMOS circuits, and NMOS circuits. Furthermore, although this embodiment shows a driver-integrated type in which a drive circuit is formed on a substrate, this is not necessarily necessary, and the drive circuit can be formed outside instead of on the substrate.

Further, the pixel portion 602 is formed of a pixel including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof. Note that an insulator 614 is formed to cover the end of the first electrode 613. The insulator 614 can be formed using a positive photosensitive resin film.

Further, in order to improve the coverage of the film formed on the insulator 614, a surface having curvature is formed at the upper end or the lower end of the insulator 614. For example, when photosensitive acrylic is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface. The radius of curvature of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. Further, as the insulator 614, either negative type or positive type photosensitive material can be used.

An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material with a large work function. For example, a single layer such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film. In addition to the film, a stacked structure of titanium nitride and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film, etc. can be used. Note that if the layered structure is used, the resistance as a wiring is low, good ohmic contact can be made, and furthermore, it can function as an anode.

Further, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. The material constituting the EL layer 616 may be a low-molecular compound or a high-molecular compound (including oligomers and dendrimers).

Furthermore, the material used for the second electrode 617, which is formed on the EL layer 616 and functions as a cathode, may be a material with a small work function (Al, Mg, Li, Ca, or an alloy or compound thereof, MgAg, MgIn, It is preferable to use AlLi, etc.). Note that when the light generated in the EL layer 616 is transmitted through the second electrode 617, the second electrode 617 is made of a thin metal film with a reduced thickness and a transparent conductive film (ITO, 2 wt% or more and 20 wt% or less). It is preferable to use a lamination with indium oxide containing zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.).

Note that a light emitting device 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device 618 is preferably a light-emitting device having the structure of Embodiment 1 or 2. Note that the pixel portion is formed with a plurality of light-emitting devices, and the light-emitting device in this embodiment includes a light-emitting device having the structure described in Embodiment 1 and Embodiment 3, and other structures. may include both light emitting devices having.

Furthermore, by bonding the sealing substrate 604 to the substrate 610 of the light emitting device using a sealant 605, a structure is created in which a light emitting device 618 is provided in a space 607 surrounded by the substrate 610, the sealing substrate 604, and the sealant 605. ing. Note that the space 607 is filled with a filler, and in addition to being filled with an inert gas (nitrogen, argon, etc.), the space 607 may also be filled with a resin, a drying material, or both.

Note that it is preferable to use epoxy resin or glass frit for the sealing material 605. Further, it is desirable that these materials are as impervious to moisture and oxygen as possible. Further, as a material for the sealing substrate 604, in addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic, or the like can be used.

In the above manner, a light-emitting device using the light-emitting device described in Embodiment 1 and Embodiment 3 can be obtained.

<Configuration example 1 of light emitting device>
FIG. 8 shows, as an example of a display device, a light-emitting device in which a light-emitting device that emits white light is formed and a colored layer (color filter) is formed therein.

FIG. 8A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral part 1042, a pixel part 1040, a drive Circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light emitting device, EL layer 1028, second electrode 1029 of the light emitting device, sealing substrate 1031, sealing material 1032, red pixel 1044R, green pixel 1044G, blue A pixel 1044B, a white pixel 1044W, etc. are illustrated.

Further, in FIGS. 8A and 8B, colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are provided on a transparent base material 1033. Further, a black layer (black matrix) 1035 may be further provided. A transparent base material 1033 provided with a colored layer and a black layer is aligned and fixed to the substrate 1001. Note that the colored layer and the black layer are covered with an overcoat layer 1036. In addition, in FIG. 8A, there is a light-emitting layer in which light does not pass through the colored layer and exits to the outside, and a light-emitting layer in which light passes through the colored layer of each color and exits to the outside.The light that does not pass through the colored layer is Since the light that passes through the white and colored layers becomes red, blue, and green, images can be expressed using pixels of four colors.

FIG. 8B shows an example in which a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As shown in FIG. 8B, a colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

In addition, in the light emitting device described above, the light emitting device has a structure (bottom emission type) in which light is extracted from the substrate 1001 side where the TFT is formed, but a structure (top emission type) in which light emission is extracted from the sealing substrate 1031 side. ) may also be used as a light emitting device.

<Configuration example 2 of light emitting device>
Cross-sectional views of a top emission type light emitting device are shown in FIGS. 9A and 9B. In this case, a substrate that does not transmit light can be used as the substrate 1001. Until the connection electrode for connecting the TFT and the anode of the light emitting device is manufactured, the manufacturing process is similar to that of a bottom emission type light emitting device. After that, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may play the role of planarization. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film 1021, as well as various other materials.

Although the lower electrode 1025W, lower electrode 1025R, lower electrode 1025G, and lower electrode 1025B of the light emitting device are assumed to be anodes here, they may be cathodes. Further, in the case of a top emission type light emitting device as shown in FIGS. 9A and 9B, the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B are preferably reflective electrodes. Note that the second electrode 1029 preferably has a function of reflecting light and a function of transmitting light. Further, it is preferable that a microcavity structure is applied between the second electrode 1029 and the lower electrode 1025W, lower electrode 1025R, lower electrode 1025G, and lower electrode 1025B to have a function of amplifying light of a specific wavelength. The structure of the EL layer 1028 is as described in Embodiment Modes 1 and 3, and has a device structure that allows white light emission.

8A, FIG. 8B, FIG. 9A, and FIG. 9B, the structure of the EL layer capable of emitting white light may be realized by using a plurality of light emitting layers, a plurality of light emitting units, or the like. Note that the configuration for obtaining white light emission is not limited to these.

In the top emission structure as shown in FIGS. 9A and 9B, sealing can be performed using a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). A black layer (black matrix) 1030 may be provided on the sealing substrate 1031 so as to be located between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black layer (black matrix) may be covered with an overcoat layer. Note that as the sealing substrate 1031, a substrate having translucency is used.

Further, although FIG. 9A shows a configuration in which full-color display is performed using three colors, red, green, and blue, full-color display may be performed using four colors, red, green, blue, and white, as shown in FIG. 9B. . Further, the configuration for performing full color display is not limited to these. For example, full-color display may be performed using four colors: red, green, blue, and yellow.

A light emitting device according to one embodiment of the present invention uses a fluorescent material as a guest material. Fluorescent materials have sharper spectra than phosphorescent materials, so they can emit light with high color purity. Therefore, by using the light-emitting device in the light-emitting device shown in this embodiment, a light-emitting device with high color reproducibility can be obtained.

(Embodiment 5)
In this embodiment, an electronic device and a display device that are one embodiment of the present invention will be described.

According to one embodiment of the present invention, a highly reliable electronic device and display device that have a flat surface and good luminous efficiency can be manufactured. Further, according to one embodiment of the present invention, a highly reliable electronic device and display device that have a curved surface and good luminous efficiency can be manufactured. Further, as described above, a light emitting device with high color reproducibility can be obtained.

Examples of electronic devices include television devices, desktop or notebook personal computers, computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio equipment. Examples include playback devices and large game machines such as pachinko machines.

The portable information terminal 900 shown in FIGS. 10A and 10B includes a housing 901, a housing 902, a display portion 903, a hinge portion 905, and the like.

The housing 901 and the housing 902 are connected by a hinge portion 905. The portable information terminal 900 can be unfolded from the folded state (FIG. 10A) as shown in FIG. 10B. This provides excellent portability when carried, and the large display area provides excellent visibility when used.

The mobile information terminal 900 is provided with a flexible display section 903 spanning a casing 901 and a casing 902 that are connected by a hinge section 905 .

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 903. Thereby, a highly reliable portable information terminal can be manufactured.

The display unit 903 can display at least one of document information, still images, moving images, and the like. When displaying document information on the display unit, the mobile information terminal 900 can be used as an electronic book terminal.

When the mobile information terminal 900 is unfolded, the display portion 903 is held in a state with a large radius of curvature. For example, the display portion 903 is held including a curved portion with a radius of curvature of 1 mm or more and 50 mm or less, preferably 5 mm or more and 30 mm or less. In a part of the display section 903, pixels are arranged continuously from the casing 901 to the casing 902, and a curved display can be performed.

The display unit 903 functions as a touch panel and can be operated with a finger, a stylus, or the like.

The display section 903 is preferably configured with one flexible display. This allows continuous display without interruption between the casings 901 and 902. Note that a configuration may be adopted in which each of the housing 901 and the housing 902 is provided with a display.

Preferably, the hinge portion 905 has a locking mechanism so that the angle between the housing 901 and the housing 902 does not become larger than a predetermined angle when the mobile information terminal 900 is unfolded. For example, the angle at which the lock is applied (it does not open further) is preferably 90 degrees or more and less than 180 degrees, typically 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. be able to. Thereby, the convenience, safety, and reliability of the mobile information terminal 900 can be improved.

When the hinge portion 905 has a locking mechanism, it is possible to prevent damage to the display portion 903 without applying excessive force to the display portion 903. Therefore, a highly reliable mobile information terminal can be realized.

The housing 901 and the housing 902 may have a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

A wireless communication module is provided in either the housing 901 or the housing 902, and is capable of transmitting and receiving data via a computer network such as the Internet, LAN (Local Area Network), or Wi-Fi (registered trademark). is possible.

The portable information terminal 910 shown in FIG. 10C includes a housing 911, a display section 912, operation buttons 913, an external connection port 914, a speaker 915, a microphone 916, a camera 917, and the like.

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 912. Thereby, portable information terminals can be manufactured with high yield.

The mobile information terminal 910 includes a touch sensor on the display section 912. All operations, such as making a call or inputting characters, can be performed by touching the display section 912 with a finger, stylus, or the like.

Further, by operating the operation button 913, the power can be turned on and off, and the type of image displayed on the display section 912 can be switched. For example, you can switch from the email creation screen to the main menu screen.

Furthermore, by providing a detection device such as a gyro sensor or an acceleration sensor inside the mobile information terminal 910, the orientation of the mobile information terminal 910 (vertical or horizontal) can be determined and the orientation of the screen display on the display unit 912 can be determined. Can be switched automatically. Furthermore, the orientation of the screen display can also be changed by touching the display section 912, operating the operation button 913, or inputting voice using the microphone 916.

The portable information terminal 910 has one or more functions selected from, for example, a telephone, a notebook, an information viewing device, and the like. Specifically, it can be used as a smartphone. The portable information terminal 910 can execute various applications such as mobile telephone, e-mail, text viewing and creation, music playback, video playback, Internet communication, games, etc., for example.

The camera 920 shown in FIG. 10D includes a housing 921, a display section 922, an operation button 923, a shutter button 924, and the like. Further, a detachable lens 926 is attached to the camera 920.

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 922. Thereby, a highly reliable camera can be manufactured.

Here, the camera 920 is configured such that the lens 926 can be removed from the housing 921 and replaced, but the lens 926 and the housing 921 may be integrated.

Camera 920 can capture still images or moving images by pressing shutter button 924. Further, the display section 922 has a function as a touch panel, and it is also possible to capture an image by touching the display section 922.

Note that the camera 920 can be separately equipped with a strobe device, a viewfinder, or the like. Alternatively, these may be incorporated into the housing 921.

FIG. 11A is a schematic diagram showing an example of a cleaning robot.

The cleaning robot 5100 has a display 5101 placed on the top, a plurality of cameras 5102 placed on the side, a brush 5103, and an operation button 5104. Although not shown, the bottom surface of the cleaning robot 5100 is provided with tires, a suction port, and the like. The cleaning robot 5100 is also equipped with various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezo sensor, an optical sensor, and a gyro sensor. Additionally, the cleaning robot 5100 is equipped with wireless communication means.

The cleaning robot 5100 is self-propelled, can detect dirt 5120, and can suck the dirt from a suction port provided on the bottom surface.

Further, the cleaning robot 5100 can analyze the image taken by the camera 5102 and determine the presence or absence of obstacles such as walls, furniture, or steps. Furthermore, if an object such as wiring that is likely to become entangled with the brush 5103 is detected through image analysis, the rotation of the brush 5103 can be stopped.

The display 5101 can display the remaining battery power, the amount of dust that has been sucked, and the like. The route traveled by the cleaning robot 5100 may be displayed on the display 5101. Further, the display 5101 may be a touch panel and the operation buttons 5104 may be provided on the display 5101.

The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by camera 5102 can be displayed on portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even from outside the home. Furthermore, the display on the display 5101 can also be checked on a portable electronic device 5140 such as a smartphone.

The light-emitting device of one embodiment of the present invention can be used for the display 5101.

The robot 2100 shown in FIG. 11B includes an arithmetic unit 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

The microphone 2102 has a function of detecting the user's speaking voice, environmental sounds, and the like. Furthermore, the speaker 2104 has a function of emitting sound. Robot 2100 can communicate with a user using microphone 2102 and speaker 2104.

Display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may include a touch panel. Further, the display 2105 may be a removable information terminal, and by installing it at a fixed position on the robot 2100, charging and data exchange are possible.

The upper camera 2103 and the lower camera 2106 have a function of capturing images around the robot 2100. Further, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the direction of movement of the robot 2100 when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 uses an upper camera 2103, a lower camera 2106, and an obstacle sensor 2107 to recognize the surrounding environment and can move safely.

The light-emitting device of one embodiment of the present invention can be used for the display 2105.

FIG. 11C is a diagram illustrating an example of a goggle-type display. The goggle type display includes, for example, a housing 5000, a display section 5001, a speaker 5003, an LED lamp 5004, operation keys (including a power switch or an operation switch), a connection terminal 5006, a sensor 5007 (force, displacement, position, speed, Measuring acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration, odor, or infrared rays a microphone 5008, a second display section 5002, a support section 5012, an earphone 5013, and the like.

The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002.

Further, FIGS. 12A and 12B show a foldable portable information terminal 5150. A foldable mobile information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. FIG. 12A shows mobile information terminal 5150 in an expanded state. FIG. 12B shows the portable information terminal 5150 in a folded state. Although the mobile information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

Display area 5152 can be folded in half by bending portion 5153. The bending portion 5153 is composed of an expandable member and a plurality of support members, and when folded, the expandable member stretches and the bending portion 5153 has a radius of curvature of 2 mm or more, preferably 5 mm or more. Folded.

Note that the display area 5152 may be a touch panel (input/output device) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used for the display area 5152.

This embodiment can be combined with other embodiments as appropriate.

(Embodiment 6)
In this embodiment, an example in which a light-emitting device of one embodiment of the present invention is applied to various lighting devices will be described with reference to FIG. 13. By using a light-emitting device that is one embodiment of the present invention, a highly reliable lighting device with good luminous efficiency can be manufactured.

By manufacturing the light-emitting device of one embodiment of the present invention over a flexible substrate, an electronic device or a lighting device that has a light-emitting region with a curved surface can be realized.

Further, a light-emitting device to which the light-emitting device of one embodiment of the present invention is applied can also be applied to lighting of a car, and for example, lighting can be installed on a windshield, a ceiling, or the like.

FIG. 13 is an example in which a light emitting device is used as an indoor lighting device 8501. Note that since the light emitting device can have a large area, it is also possible to form a large area illumination device. In addition, by using a housing with a curved surface, the lighting device 8502 whose light-emitting region has a curved surface can also be formed. The light-emitting device shown in this embodiment has a thin film shape, and has a high degree of freedom in designing the housing. Therefore, lighting devices with various elaborate designs can be formed. Furthermore, a large lighting device 8503 may be provided on the wall of the room. Further, a touch sensor may be provided in the lighting devices 8501, 8502, and 8503 to turn the power on or off.

Further, by using a light-emitting device on the surface side of the table, the lighting device 8504 can function as a table. Note that by using a light emitting device in a part of other furniture, it is possible to obtain a lighting device that functions as furniture.

In the above manner, a lighting device and an electronic device can be obtained by applying the light-emitting device of one embodiment of the present invention. Note that the lighting devices and electronic devices that can be applied are not limited to those shown in this embodiment, and can be applied to electronic devices in all fields.

Further, the structure shown in this embodiment can be used in combination with the structures shown in other embodiments as appropriate.

In this example, examples of manufacturing a light-emitting device of one embodiment of the present invention and a comparative light-emitting device, and characteristics of the light-emitting devices will be described. The configuration of the light emitting device manufactured in this example is the same as that shown in FIG. 1A. Details of the device structure are shown in Tables 1 to 6. Note that the value represented by x ₁ in Tables 1 to 4 is the value represented in Table 5, and the value represented by x ₂ is the value represented in Table 6. Furthermore, the structures and abbreviations of the compounds used are shown below.

<Production of light emitting device>
A method for manufacturing the light emitting device manufactured in this example will be described below.

<<Production of light emitting devices 2 to 5>>
An ITSO film was formed as an electrode 101 on a glass substrate to a thickness of 70 nm. Note that the electrode area of the electrode 101 was 4 mm ² (2 mm x 2 mm).

Next, as a hole injection layer 111 on the electrode 101, DBT3P-II and molybdenum oxide (MoO ₃ ) are mixed at a weight ratio (DBT3P-II:MoO ₃ ) of 1:0.5. Co-deposition was performed to a thickness of 40 nm.

Next, PCCP was deposited as a hole transport layer 112 on the hole injection layer 111 to a thickness of 20 nm.

Next, as a light emitting layer 130 on the hole transport layer 112, mPCCzPTzn-02, PCCP and Ir(mpptz-diBuCNp) ₃ , and 2tBu-ptBuDPhA2Anth were mixed in a weight ratio (mPCCzPTzn-02:PCCP:Ir(mpptz- Co-evaporation was performed so that diBuCNp) ₃ :2tBu-ptBuDPhA2Anth) was 0.5:0.5:0.1: _x1 and the thickness was 30 nm. Next, mPCCzPTzn-02, PCCP, Ir(mpptz-diBuCNp) ₃ , and 2tBu-ptBuDPhA2Anth were mixed at a weight ratio of (mPCCzPTzn-02:PCCP:Ir(mpptz-diBuCNp) ₃ :2tB). u-ptBuDPhA2Anth) is 0.8 :0.2:0.1: _x1 and the thickness was 10 nm. In the light emitting layer 130, Ir(mpptz-diBuCNp) ₃ is a phosphorescent material having a 5-membered ring. Further, 2tBu-ptBuDPhA2Anth is a fluorescent material having a protecting group. Furthermore, the value of x ₁ differs depending on each light emitting device, and the value of x ₁ in each light emitting device is the value shown in Table 5.

Next, as the electron transport layer 118, mPCCzPTzn-02 was sequentially deposited on the light emitting layer 130 to have a thickness of 20 nm, and NBPhen had a thickness of 10 nm. Next, on the electron transport layer 118, LiF was deposited to a thickness of 1 nm as an electron injection layer 119.

Next, aluminum (Al) was formed as the electrode 102 on the electron injection layer 119 to a thickness of 200 nm.

Next, in a glove box with a nitrogen atmosphere, a glass substrate for sealing is fixed to a glass substrate on which an organic material is formed using an organic EL sealing material, so that the light emitting devices 2 to 5 are sealed. Sealed. Specifically, a sealant is applied around an organic material formed on a glass substrate, the glass substrate and a glass substrate for sealing are bonded together, and ultraviolet light with a wavelength of 365 nm is irradiated at 6 J/ ^cm2 . , heat-treated at 80° C. for 1 hour. Through the above steps, light emitting devices 2 to 5 were obtained.

≪Light-emitting device 7 to light-emitting device 10, light-emitting device 12 to light-emitting device 15, light-emitting device 17 to light-emitting device 19, light-emitting device 21 to light-emitting device 24, light-emitting device 26 to light-emitting device 28, light-emitting device 30 to light-emitting device 33, comparison Preparation of light emitting devices 1, 6, 11, 16, 20, 25, 29 and comparative light emitting devices 34 to 38≫
Light emitting device 7 to light emitting device 10, light emitting device 12 to light emitting device 15, light emitting device 17 to light emitting device 19, light emitting device 21 to light emitting device 24, light emitting device 26 to light emitting device 28, light emitting device 30 to light emitting device 33, comparative light emission Devices 1, 6, 11, 16, 20, 25, and 29 and comparative light-emitting devices 34 to 38 were fabricated using the vacuum evaporation method in the same manner as light-emitting devices 2 to 5 shown above. Since the details of the structure of the light emitting device are as shown in Tables 1 to 4, details of the manufacturing method will be omitted. Note that in Tables 1 to 4, the values represented by x ₁ are as shown in Table 5, and the values represented by x ₂ are as shown in Table 6.

Comparative light emitting devices 1, 6, 11, 16, 20, 25, 29 and comparative light emitting device 34 are light emitting devices in which the light emitting layer 130 does not contain a fluorescent material. Therefore, the device is a light-emitting device in which the phosphorescent material contained in each light-emitting layer emits light. These light-emitting devices are light-emitting devices in which a phosphorescent material functions as a guest material (energy acceptor), and are shown as comparative examples of the light-emitting devices of one embodiment of the present invention in which a phosphorescent material functions as an energy donor.

The light emitting devices 2 to 5, the light emitting devices 7 to 10, the light emitting devices 12 to 15, the light emitting devices 21 to 24, the light emitting devices 26 to 28, and the light emitting devices 30 to 33 are according to the present invention. This is a light-emitting device according to one embodiment. Each light-emitting layer 130 includes 2tBu-ptBuDPhA2Anth, which is a fluorescent material having a protective group. Therefore, it is a light-emitting device that emits fluorescent light. Note that the comparative light emitting devices 35 to 38 are also fluorescent light emitting devices having 2tBu-ptBuDPhA2Anth, which is a fluorescent material having a protective group in the light emitting layer 130.

In the light-emitting devices 2 to 5, Ir(mpptz-diBuCNp) ₃ is used as the phosphorescent material having a 5-membered ring, and in the light-emitting devices 7 to 10, Ir(mpptz-diPrp) is used as the phosphorescent material having the 5-membered ring. ) ₃ as a phosphorescent material having a 5-membered ring in the light-emitting devices 12 to 15, and Ir(Mptz1-mp) ₃ as a phosphorescent material having a 5-membered ring in the light-emitting devices 17 to 19. (pbi-diBuCNp) ₃ is used as a phosphorescent material having a 5-membered ring in the light-emitting devices 20 to 24, and fac-Ir(pbi-diBup) ₃ is used as a phosphorescent material having a 5-membered ring in the light-emitting devices 26 to 28. Ir(pni-diBup) ₂ (mdppy) is used as the phosphorescent material, and Ir(pni-diBup) ₃ is used as the phosphorescent material having a five-membered ring in the light emitting devices 30 to 33. The above-mentioned phosphorescent material having a five-membered ring is an example of a phosphorescent material having a triazole skeleton or an imidazole skeleton. Note that comparative light-emitting devices 35 to 38 use Ir(ppy) ₃ , which is a phosphorescent material that does not have a five-membered ring skeleton, and their device characteristics are compared with the light-emitting device of one embodiment of the present invention. was created to.

Note that mPCCzPTzn-02 and PCCP are a combination that forms an exciplex, and 4,6mCzP2Pm and PCCP are a combination that forms an exciplex.

<Characteristics of light emitting device>
Next, the light-emitting devices 2 to 5, the light-emitting devices 7 to 10, the light-emitting devices 12 to 15, the light-emitting devices 17 to 19, the light-emitting devices 21 to 24, and the light-emitting devices 26 to 10 produced above The characteristics of the light emitting device 28, the light emitting devices 30 to 33, the comparative light emitting devices 1, 6, 11, 16, 20, 25, 29, and the comparative light emitting devices 34 to 38 were measured. A color luminance meter (BM-5A, manufactured by Topcon) was used to measure the luminance and CIE chromaticity, and a multichannel spectrometer (PMA-11, manufactured by Hamamatsu Photonics) was used to measure the electroluminescence spectrum.

Light emitting device 2 to light emitting device 5, light emitting device 7 to light emitting device 10, light emitting device 12 to light emitting device 15, light emitting device 17 to light emitting device 19, light emitting device 21 to light emitting device 24, light emitting device 26 to light emitting device 28, and light emitting device 14, 16, 18, 20, 22 show external quantum efficiency-luminance characteristics of light-emitting devices 30 to 33, comparative light-emitting devices 1, 6, 11, 16, 20, 25, 29, and comparative light-emitting devices 34 to 38. , 24, 26, and 28, respectively. Furthermore, the light emitting devices 2 to 5, the light emitting devices 7 to 10, the light emitting devices 12 to 15, the light emitting devices 17 to 19, the light emitting devices 21 to 24, the light emitting devices 26 to 28, and A current was passed through each of the light emitting devices 30 to 33, comparative light emitting devices 1, 6, 11, 16, 20, 25, 29, and comparative light emitting devices 34 to 38 at a current density of 2.5 mA/ ^cm2 . The electroluminescence spectra obtained are shown in FIGS. 15, 17, 19, 21, 23, 25, 27, and 29, respectively. Note that the measurements of each light emitting device were performed at room temperature (atmosphere maintained at 23° C.).

Furthermore, light emitting devices 2 to ⁵ , light emitting devices 7 to 10, light emitting devices 12 to 15, light emitting devices 17 to 19, light emitting devices 21 to 24, light emitting devices 2 to 5, light emitting devices 12 to 15, light emitting devices 17 to 19, light emitting devices 21 to 24, Tables 7 and 8 show the device characteristics of devices 26 to 28, light-emitting devices 30 to 33, comparative light-emitting devices 1, 6, 11, 16, 20, 25, 29, and comparative light-emitting devices 34 to 38. Shown below.

<Energy transfer from energy donor (phosphorescent material with 5-membered ring skeleton) to energy acceptor (fluorescent material with protective group)>
As shown in FIG. 15, the emission spectra of Light Emitting Devices 2 to 5 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 528 nm and a half-width of around 62 nm. On the other hand, the emission spectrum of Comparative Light Emitting Device 1 showed light emission originating from Ir(mpptz-diBuCNp) ₃ with a peak wavelength of 492 nm and a half width of 67 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 17, the emission spectra of Light Emitting Devices 7 to 10 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 530 nm and a half-width of around 66 nm. On the other hand, the emission spectrum of Comparative Light Emitting Device 6 showed light emission derived from Ir(mpptz-diPrp) ₃ with a peak wavelength of 508 nm and a half width of 85 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 19, the emission spectra of the light-emitting devices 12 to 15 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 529 nm and a half-width of around 64 nm. On the other hand, the emission spectrum of comparative light emitting device 11 showed light emission originating from Ir(Mptz1-mp) ₃ with a peak wavelength of 502 nm and a half width of 91 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 21, the emission spectrum of the comparative light emitting device 16 showed emission originating from Ir(pbi-diBuCNp) ₃ with a maximum peak wavelength of 513 nm and a half width of 64 nm. The emission spectrum of light emitting device 17 is different from the emission spectrum of comparison light emitting device 16. This is because both the luminescence derived from Ir(pbi-diBuCNp) ₃ and the luminescence derived from 2tBu-ptBuDPhA2Anth are observed. Therefore, it can be seen that fluorescent light emission is obtained from the light emitting device 17. Furthermore, the emission spectra of the light-emitting device 18 and the light-emitting device 19 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 535 nm and a half-width of around 69 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 23, the emission spectrum of the comparative light emitting device 20 showed light emission originating from fac-Ir(pbi-diBup) ₃ , with a maximum peak wavelength of 508 nm and a half width of 64 nm. The emission spectrum of light emitting device 21 is different from the emission spectrum of comparison light emitting device 20. This is because both the luminescence derived from fac-Ir(pbi-diBup) ₃ and the luminescence derived from 2tBu-ptBuDPhA2Anth are observed. Therefore, it can be seen that fluorescent light is emitted from the light emitting device 21. Furthermore, the emission spectra of the light-emitting devices 22 to 24 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 538 nm and a half-width of around 69 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 25, the emission spectrum of the comparative light emitting device 25 showed light emission originating from Ir(pni-diBup) ₂ (mdppy) with a maximum peak wavelength of 525 nm and a half width of 73 nm. The emission spectrum of light emitting device 26 is different from the emission spectrum of comparison light emitting device 25. This is because both the luminescence derived from Ir(pni-diBup) ₂ (mdppy) and the luminescence derived from 2tBu-ptBuDPhA2Anth are observed. Therefore, it can be seen that fluorescent light is emitted from the light emitting device 26. Furthermore, the emission spectra of the light-emitting device 27 and the light-emitting device 28 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 535 nm and a half-width of around 69 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 27, the emission spectrum of the comparative light emitting device 29 showed light emission derived from Ir(pni-diBup) ₃ with a maximum peak wavelength of 500 nm and a half width of 59 nm. The emission spectrum of light emitting device 30 is different from the emission spectrum of comparison light emitting device 29. This is because both the luminescence derived from Ir(pni-diBup) ₃ and the luminescence derived from 2tBu-ptBuDPhA2Anth are observed. Therefore, it can be seen that fluorescent light is emitted from the light emitting device 29. Furthermore, the emission spectra of the light-emitting devices 31 to 33 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 536 nm and a half-width of around 65 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

As shown in FIG. 29, the emission spectrum of the comparative light emitting device 34 showed emission originating from Ir(ppy) ₃ with a maximum peak wavelength of 517 nm and a half width of 70 nm. Furthermore, the emission spectra of Comparative Light Emitting Device 35 to Comparative Light Emitting Device 38 showed green light emission originating from 2tBu-ptBuDPhA2Anth, with a peak wavelength of around 535 nm and a half-width of around 69 nm.

Light emitting device 2 to light emitting device 5, light emitting device 7 to light emitting device 10, light emitting device 12 to light emitting device 15, light emitting device 17 to light emitting device 19, light emitting device 21 to light emitting device 24, light emitting device 26 to light emitting device 28, and light emitting device 16, FIG. 18, FIG. 20, FIG. 22, FIG. 24, FIG. 26, Tables 7 and 8, Even in a light-emitting device with a high concentration of 2tBu-ptBuDPhA2Anth, which is a fluorescent material, a high luminous efficiency exceeding at least an external quantum efficiency of 14% was exhibited. Further, light-emitting devices 2 to 5, light-emitting devices 7 to 10, light-emitting devices 12 to 15, light-emitting devices 17 to 19, light-emitting devices 21 to 19, which are light-emitting devices of one embodiment of the present invention, Device 24, light-emitting device 26 to light-emitting device 28, and light-emitting device 30 to light-emitting device 33 exhibited higher external quantum efficiencies than comparative light-emitting device 37 at all concentrations.

Since the probability of generating singlet excitons generated by recombination of carriers (holes and electrons) injected from a pair of electrodes is 25% at maximum, if the efficiency of light extraction to the outside is 30%, fluorescence The maximum external quantum efficiency of a light emitting device is 7.5%. However, in the light emitting devices 2 to 5, the light emitting devices 7 to 10, the light emitting devices 12 to 15, the light emitting devices 21 to 24, the light emitting devices 26 to 28, and the light emitting devices 30 to 33, The external quantum efficiency is higher than 7.5%. This is because, in addition to the light emission originating from singlet excitons generated by the recombination of carriers (holes and electrons) injected from a pair of electrodes, the emission originating from energy transfer from triplet excitons causes fluorescence. This is because it is obtained from the material. From these results, in the light-emitting device of one embodiment of the present invention, by using a fluorescent material having a protecting group and a phosphorescent material having a five-membered ring skeleton, non-radiative deactivation of triplet excitons is suppressed and light emission is achieved. It can be said that both singlet excitation energy and triplet excitation energy generated in the layer are efficiently converted into light emission from the fluorescent material.

<Overlap of the absorption spectrum of the fluorescent material and the emission spectrum of the phosphorescent material having a 5-membered ring>
Next, the relationship between the absorption spectrum of the fluorescent material 2tBu-ptBuDPhA2Anth and the EL emission spectrum of the phosphorescent material used in each light-emitting device was investigated. The results are shown in FIGS. 30 to 36.

As mentioned above, Comparative Light Emitting Devices 1, 6, 11, 16, 20, 25, and 29 exhibit light emission derived from the phosphorescent materials used in their respective light emitting layers. It can be seen from FIGS. 30 to 36 that the emission spectra of each phosphorescent material and the absorption spectrum of 2tBu-ptBuDPhA2Anth overlap. Therefore, when each phosphorescent material and 2tBu-ptBuDPhA2Anth are both used in the light emitting layer, energy transfer from each phosphorescent material to 2tBu-ptBuDPhA2Anth can occur. Here, as described above, the light-emitting device of one embodiment of the present invention exhibits high luminous efficiency. That is, it can be seen that the deactivation of triplet excitons in the light emitting layer, which would occur in a normal fluorescent element, is suppressed. This is the effect of using a fluorescent material with a protecting group. In addition, by using a phosphorescent material having a five-membered ring, recombination of carriers in the fluorescent material is suppressed, and energy transfer of triplet excitons from the phosphorescent material to the fluorescent material by the Dexter mechanism and the effect of suppressing the energy deactivation of triplet excitons.

<Change in external quantum efficiency due to guest material concentration>
FIG. 37 shows the relationship between guest material concentration and external quantum efficiency in a light emitting device using each phosphorescent material. From FIG. 37, the light-emitting device of one embodiment of the present invention using a phosphorescent material having a 5-membered ring is compared to the comparative light-emitting devices 34 to 34 using Ir(ppy) ₃ , which is a phosphorescent material not having a 5-membered ring skeleton. It can be seen that, compared to No. 38, the decrease in external quantum efficiency due to an increase in the concentration of the fluorescent material is suppressed. By using a guest material with a protecting group in the light-emitting layer and a phosphorescent material with a 5-membered ring, triplet excitation energy can be transferred from the host material to the guest material by the Dexter mechanism, and triplet excitation can be achieved. This is because deactivation of energy is suppressed. Furthermore, by increasing the concentration of the guest material, the energy transfer of excitation energy from the host material to the guest material by the Förster mechanism can be efficiently utilized, so both triplet excitation energy and singlet excitation energy in the emissive layer can be used to fluoresce. This is because it can be efficiently converted into luminescence of a transparent material. From the above, it was found that a light-emitting device of one embodiment of the present invention can have a high guest material concentration and high luminous efficiency.

It has also been shown that in light emitting devices using Ir(mpptz-diPrp) ₃ and Ir(Mptz1-mp) ₃ , the luminous efficiency can be improved by increasing the guest material concentration.

<Reliability measurement of light emitting devices>
Next, light emitting devices 2 to 5, light emitting devices 7 to 10, light emitting devices 12 to 15, light emitting devices 17 to 19, light emitting devices 21 to 24, light emitting devices 26 to 28 A constant current drive test at 2.0 mA was conducted for Light Emitting Devices 30 to 33 and Comparative Light Emitting Devices 1, 6, 11, 16, 20, 25, and 29. The results are shown in FIGS. 38 to 44. From FIGS. 38 to 44, it was found that increasing the guest material concentration improved reliability. This suggests that by increasing the guest material concentration, the excitation energy in the light emitting layer can be efficiently converted into light emission from the guest material. That is, it is suggested that by increasing the guest material concentration, the energy transfer rate of triplet excitation energy from the host material to the guest material by the Förster mechanism can be increased.

Here, in the light-emitting layer, energy transfer from the energy donor to the guest material, that is, energy transfer related to light emission, competes with the quenching process due to the influence of impurities and deterioration substances. Therefore, in order to obtain a highly reliable light emitting device, it is important to increase the energy transfer rate related to light emission.

<Measurement of fluorescence lifetime of light emitting devices>
Next, in order to investigate the difference in luminescence speed depending on the concentration of the guest material, light-emitting devices 2 to 5, light-emitting devices 7 to 10, light-emitting devices 12 to 15, and comparative light-emitting devices 1, 6, The fluorescence lifetime of 11 samples was measured. A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, in order to measure the lifetime of fluorescence emission in a light-emitting device, a rectangular pulse voltage was applied to the light-emitting device, and the emission that attenuated from the fall of the voltage was measured in time-resolved manner using a streak camera. A pulse voltage was applied at a cycle of 10 Hz, and data with a high S/N ratio was obtained by integrating the repeatedly measured data. In addition, the measurement was performed at room temperature (300 K), and the applied pulse voltage was applied at around 3 V to 4 V so that the luminance of the light emitting device was around 1000 cd/ ^m2 , the applied pulse time width was 100 μs, and the negative bias voltage was -5 V ( (when the element drive is OFF), and the measurement time range was 10 μsec. The measurement results are shown in FIGS. 49 to 51. Note that in FIGS. 49 to 51, the vertical axis indicates the intensity normalized by the emission intensity in a state where carriers are constantly injected (when the pulse voltage is ON). Further, the horizontal axis indicates the elapsed time from the fall of the pulse voltage.

When fitting the attenuation curves shown in FIGS. 49 to 51 using an exponential function, it was found that from light-emitting devices 2 to 5, light-emitting devices 7 to 10, a fast fluorescence component of 0.4 μs or less and a fluorescence component of 2 μs It was found that the light-emitting devices 12 to 15 emitted light with a fast fluorescent component of 0.4 μsec or less and a delayed fluorescent component of about 4 μsec. It was also found that when a fluorescent material is added as a guest material, the higher the concentration of the fluorescent material, the higher the proportion of fast fluorescent components increases, and the proportion of delayed fluorescent components decreases. Further, the comparative light-emitting device 1 emits light from a phosphorescent material, and emits light having a fast fluorescent component of 0.5 μsec or less and a delayed fluorescent component of about 4 μsec, and the comparative light-emitting device 6 and the comparative light-emitting device 11 It was found that the phosphorescent material emits light, which has a fast fluorescent component of 0.5 μsec or less and a delayed fluorescent component of about 2 μsec.

From these results, it can be seen that by adding a fluorescent material as a guest material to the light emitting layer, the light emission rate becomes faster and the proportion of light emitted by fast fluorescent components originating from the fluorescent material increases.
Here, as described above, the light-emitting devices 2 to 5, the light-emitting devices 7 to 10, and the light-emitting devices 12 to 15, which are one embodiment of the present invention, have a high concentration of fluorescent material. It also shows high external quantum efficiency. That is, it can be seen that the light-emitting device of one embodiment of the present invention exhibits high luminous efficiency even when the proportion of light emitted from the fluorescent material increases. Therefore, in the light-emitting device of one embodiment of the present invention, energy transfer and deactivation of triplet excitation energy from the host material to the guest material due to the Dexter mechanism can be suppressed, so the concentration of the guest material can be reduced. This suggests that the energy transfer efficiency of excitation energy by the Förster mechanism can be improved. Therefore, in the light-emitting device of one embodiment of the present invention, both singlet excitation energy and triplet excitation energy in the light-emitting layer can be efficiently used for light emission.

Further, as shown in FIGS. 49 to 51, in order to increase the energy transfer rate, it is preferable to increase the concentration of the guest material in the light emitting layer. The light-emitting device of one embodiment of the present invention can increase the energy transfer rate due to the Förster mechanism while suppressing energy transfer due to the Dexter mechanism, and can achieve good luminous efficiency by reducing the influence of competition with the quenching process. It is possible to obtain a light-emitting device having good reliability while having the following characteristics. In addition, each comparative light-emitting device emits phosphorescence and therefore has a long luminescence lifetime, but the light-emitting device of one embodiment of the present invention emits fluorescent light and therefore has a short luminescence lifetime. Therefore, the influence of competition with the above-mentioned quenching process can be reduced. As described above, in the light-emitting device of one embodiment of the present invention, the concentration of the guest material can be increased, and a light-emitting device with good luminous efficiency and reliability can be obtained.

In this example, a manufacturing example of a light-emitting device of one embodiment of the present invention different from Example 1 and a comparative light-emitting device, and characteristics of the light-emitting devices will be described. The configuration of the light emitting device manufactured in this example is the same as that shown in FIG. 1A. Details of the device structure are shown in Table 9. Furthermore, the structures and abbreviations of the compounds used are shown below. Note that for other organic compounds, the previous examples and embodiments may be referred to.

<<Production of comparative light emitting device 39 and light emitting devices 40 to 43>>
Comparative light-emitting device 39 and light-emitting devices 40 to 43 were manufactured using the vacuum evaporation method in the same manner as light-emitting devices 2 to 5 shown above. The details of each light emitting device structure are as shown in Tables 9 and 10, so details of the manufacturing method will be omitted. Note that the value represented by x ₃ in Table 9 is as shown in Table 10.

Note that in the comparative light emitting device 39, Ir(pbi-diBuCNp) ₃ , which is a phosphorescent material, functions as an energy acceptor. This is shown as a comparative example of a light-emitting device of one embodiment of the present invention in which a phosphorescent material functions as an energy donor.

<Characteristics of light emitting device>
Next, the characteristics of the comparative light emitting device 39 and the light emitting devices 40 to 43 produced above were measured. Note that the measurement method is the same as in Example 1.

FIG. 52 shows the external quantum efficiency-luminance characteristics of comparative light-emitting device 39 and light-emitting devices 40 to 43. Further, FIG. 53 shows the electroluminescence spectra when a current was applied to each of the comparative light emitting device 39 and the comparative light emitting devices 40 to 43 at a current density of 2.5 mA/cm ² . Note that the measurements of each light emitting device were performed at room temperature (atmosphere maintained at 23° C.).

Further, Table 11 shows device characteristics of comparative light emitting device 39 and comparative light emitting devices 40 to 43 at around 1000 cd/m ² .

<Energy transfer from energy donor (phosphorescent material with 5-membered ring skeleton) to energy acceptor (fluorescent material with protective group)>
As shown in FIG. 53, the emission spectra of the light emitting devices 40 to 43 showed green light emission originating from 2,6tBu-mmtBuDPhA2Anth, with a peak wavelength of around 520 nm and a half-width of around 69 nm. On the other hand, the emission spectrum of comparative light emitting device 39 showed light emission originating from Ir(pbi-diBuCNp) ₃ with a peak wavelength of 513 nm and a half width of 63 nm. Therefore, it was found that in the light-emitting device of one embodiment of the present invention, energy transfer occurs from the phosphorescent material to the fluorescent material.

Although the light emitting devices 40 to 43 exhibit light emission derived from fluorescent materials, as shown in FIG. 52 and Table 11, even light emitting devices with a high concentration of fluorescent materials have an external quantum efficiency of at least 15. It showed a high luminous efficiency exceeding %. From these results, in the light-emitting device of one embodiment of the present invention, by using a fluorescent material having a protecting group and a phosphorescent material having a five-membered ring skeleton, non-radiative deactivation of triplet excitons is suppressed and light emission is achieved. It can be said that both singlet excitation energy and triplet excitation energy generated in the layer are efficiently converted into light emission from the fluorescent material.

<Reliability measurement of light emitting devices>
Next, a constant current drive test at 2.0 mA was performed on comparative light emitting device 39 and light emitting devices 40 to 43. The results are shown in FIG. It was found from FIG. 54 that reliability improved as the guest material concentration was increased. This suggests that by increasing the guest material concentration, the excitation energy in the light emitting layer can be efficiently converted into light emission from the guest material. That is, it is suggested that by increasing the guest material concentration, the energy transfer rate of triplet excitation energy from the host material to the guest material by the Förster mechanism can be increased.

<Measurement of fluorescence lifetime of light emitting devices>
Next, in order to investigate the difference in luminescence speed depending on the concentration of the guest material, the fluorescence lifetimes of the comparison light-emitting device 39 and the light-emitting devices 40 to 43 were measured. Measurements were performed in the same manner as in Example 1. The results are shown in FIG.

From FIG. 55, it was found that the higher the concentration of the fluorescent material (guest material), the higher the proportion of fluorescent components with a faster luminescence rate, and the lower the proportion of delayed fluorescent components. From these results, it can be seen that by adding a fluorescent material as a guest material to the light emitting layer, the light emission rate becomes faster and the proportion of light emitted by fast fluorescent components originating from the fluorescent material increases.

Here, as described above, the light-emitting devices 40 to 43, which are one embodiment of the present invention, exhibit high external quantum efficiency even if the light-emitting devices have a high concentration of fluorescent material. That is, it can be seen that the light-emitting device of one embodiment of the present invention exhibits high luminous efficiency even when the proportion of light emitted from the fluorescent material increases. Therefore, in the light-emitting device of one embodiment of the present invention, energy transfer and deactivation of triplet excitation energy from the host material to the guest material due to the Dexter mechanism can be suppressed, so the concentration of the guest material can be reduced. This suggests that the energy transfer efficiency of excitation energy by the Förster mechanism can be improved. Therefore, in the light-emitting device of one embodiment of the present invention, both singlet excitation energy and triplet excitation energy in the light-emitting layer can be efficiently used for light emission.

(Reference example 1)
In this reference example, a method for synthesizing 2tBu-ptBuDPhA2Anth, which is a fluorescent material having a protecting group used in Example 1, will be described.

1.2 g (3.1 mmol) of 2-tert-butylanthracene, 1.8 g (6.4 mmol) of bis(4-tert-butylphenyl)amine, and 1.2 g (13 mmol) of sodium t-butoxide. , 60 mg (0.15 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl (abbreviation: SPhos) was placed in a 200 mL three-necked flask, and the inside of the flask was purged with nitrogen. 35 mL of mesitylene was added to this mixture, and the mixture was degassed under reduced pressure. 40 mg (70 μmol) of bis(dibenzylideneacetone)palladium(0) was added to the mixture, and the mixture was heated at 170°C for 4 hours under a nitrogen stream. Stirred.

After stirring, 400 mL of toluene was added to the resulting mixture, and then Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 066-05265), Celite (Wako Pure Chemical Industries, Ltd., catalog number: 537-02305), oxidation A filtrate was obtained by suction filtration through aluminum. The obtained filtrate was concentrated to obtain a brown solid.

This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene 9:1) to obtain the desired yellow solid. The obtained yellow solid was recrystallized from toluene, hexane, and ethanol to obtain 1.5 g of the desired yellow solid in a yield of 61%. This synthesis scheme is shown in (A-1) below.

1.5 g of the obtained yellow solid was purified by sublimation using a train sublimation method. Sublimation purification was performed by heating the yellow solid at 315° C. for 15 hours under a pressure of 4.5 Pa. After sublimation purification, the target yellow solid was obtained in a yield of 1.3 g with a recovery rate of 89%.

In addition, the results of ¹ H-NMR measurement of the yellow solid obtained in this synthesis are shown below. Furthermore, ¹ H-NMR charts are shown in FIGS. 45 and 46. Note that FIG. 45B is an enlarged view of the range from 6.5 ppm to 9.0 ppm in FIG. 45A. Moreover, FIG. 46 is an enlarged view of the range of 0.5 ppm to 2.0 ppm in FIG. 45A. From this result, it was found that the target product, 2tBu-ptBuDPhA2Anth, was obtained.

¹ H-NMR (CDCl ₃ , 300 MHz): σ = 8.20-8.13 (m, 2H), 8.12 (d, J = 8.8 Hz, 1H), 8.05 (d, J = 2 .0Hz, 1H), 7.42 (dd, J = 9.3Hz, 2.0Hz, 1H), 7.32-7.26 (m, 2H) 7.20 (d, J = 8.8Hz, 8H) ), 7.04 (dd, J=8.8Hz, 2.4Hz, 8H), 1.26 (s, 36H), 1.18 (s, 9H).

(Reference example 2)
In this reference example, a method for synthesizing Ir(pni-diBup) ₃ , which is an example of the phosphorescent material having a five-membered ring used in Example 1, will be described.

<Step 1: Synthesis of 2,6-diisobutylaniline>
2,6-dichloroaniline 100g (617mmol), isobutylboronic acid 230g (2256mmol), tripotassium phosphate 479g (2256mmol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos) 10g (24 .7 mmol) and 3000 mL of toluene were placed in a 5000 mL three-necked flask, the inside of the flask was replaced with nitrogen, and the mixture was degassed by stirring while reducing the pressure inside the flask. After degassing, 11 g (11.5 mmol) of tris(dibenzylideneacetone)dipalladium(0) was added, and the mixture was stirred at 120° C. for 12 hours under a nitrogen stream. After a predetermined period of time had passed, the resulting reaction solution was filtered under suction. The obtained filtrate was purified by extraction using toluene. Thereafter, it was purified by silica gel column chromatography. Hexane:toluene=15:1 was used as a developing solvent. The obtained fraction was concentrated to obtain 79 g of the target black oil in a yield of 62%. The synthesis scheme of Step 1 is shown in the following formula (B-1).

<Step 2; Synthesis of 2-nitronaphthalene-1-trifluoromethanesulfonate>
35 g (182 mmol) of 2-nitro-1-naphthol, 500 mL of dehydrated dichloromethane, and 51 mL (365 mmol) of triethylamine were placed in a 1000 mL three-neck flask, the inside of the flask was purged with nitrogen, and the flask was cooled to 0°C. Here, 40 mL (243 mmol) of trifluoromethanesulfonic anhydride (abbreviation: Tf ₂ O) was added dropwise, and the mixture was stirred at 0° C. for 1 hour and then at room temperature for 20 hours. After a predetermined period of time, 300 mL of water and 30 mL of 1M hydrochloric acid were added to the resulting mixture. This mixture was then purified by extraction with dichloromethane. Thereafter, it was purified by silica gel column chromatography. Hexane:dichloromethane=5:1 was used as a developing solvent. The obtained fraction was concentrated to obtain 47 g of a yellow oil, which was the desired product, in a yield of 80%. The synthesis scheme of Step 2 is shown in the following formula (B-2).

<Step 3; Synthesis of N-(2,6-diisobutylphenyl)-2-nitro-1-naphthalenamine>
30 g (146 mmol) of 2,6-diisobutylaniline synthesized in Step 1, 47 g (146 mmol) of 2-nitronaphthalene-1-trifluoromethanesulfonate synthesized in Step 2, 81 g (248 mmol) of cesium carbonate, and 750 mL of toluene in a 2000 mL three-necked flask. The inside of the flask was replaced with nitrogen, and the mixture was degassed by stirring while reducing the pressure inside the flask. After degassing, 4.8 g (11.7 mmol) of S-phos and 2.7 g (2.9 mmol) of tris(dibenzylideneacetone)dipalladium(0) were added, and the mixture was stirred at 130° C. for 28 hours under a nitrogen stream. After a predetermined period of time had elapsed, the resulting reaction mixture was purified by extraction with toluene. Thereafter, it was purified by silica gel column chromatography. Hexane:ethyl acetate=15:1 was used as a developing solvent. The resulting fractions were concentrated to give 13 g of a yellow oil with a yield of 23%. The synthesis scheme of Step 3 is shown in the following formula (B-3).

<Step 4; Synthesis of N-(2,6-diisobutylphenyl)-1,2-naphthalenediamine>
13 g (34 mmol) of N-(2,6-diisobutylphenyl)-2-nitro-1-naphthalenamine synthesized in Step 3, 6.1 mL (0.34 mol) of water, and 400 mL of ethanol were placed in a 1000 mL three-necked flask and stirred. . 32 g (0.17 mol) of tin(II) chloride was added to this mixture, and the mixture was stirred at 80° C. for 5 hours under a nitrogen stream. After a predetermined period of time had elapsed, the resulting reaction mixture was poured into 500 mL of a 2M aqueous sodium hydroxide solution and stirred at room temperature for 2 hours. The deposited precipitate was suction filtered and washed with chloroform to obtain a filtrate. The obtained filtrate was purified by extraction using chloroform. Thereafter, it was purified by silica gel column chromatography. Hexane:ethyl acetate=15:1 was used as a developing solvent. The obtained fraction was concentrated to obtain 9.5 g of the target black oil in a yield of 81%. The synthesis scheme of Step 4 is shown in the following formula (B-4).

<Step 5; Synthesis of 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBup)>
Put 9.5 g (27 mmol) of N-(2,6-diisobutylphenyl)-1,2-naphthalenediamine synthesized in step 4, 100 mL of acetonitrile, and 2.9 g (27 mmol) of benzaldehyde into a 300 mL eggplant flask, and heat at 100°C for 6 hours. Stir for hours. 0.044 g (0.274 mmol) of iron(III) chloride was added to this mixture, and the mixture was stirred at 100° C. for 16 hours. After a predetermined time, the obtained reaction mixture was extracted with ethyl acetate, and 100 mL of toluene and 10 g of manganese (IV) oxide were added to the obtained oil in a 300 mL eggplant flask, and the mixture was stirred at 130° C. for 7 hours. After a predetermined period of time, the resulting reaction mixture was suction filtered through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 537-02305)/Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 066-05265)/aluminum oxide. did. The obtained filtrate was concentrated to obtain an oily substance. The obtained oil was purified by silica gel column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain 7.9 g of a white solid, which was the target product, in a yield of 66%. The synthesis scheme of Step 5 is shown in the following formula (B-5).

<Step 6; Di-μ-chloro-tetrakis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN3]phenyl-κC}diiridium (III) Synthesis of (abbreviation: [Ir(pni-diBup) ₂ Cl] ₂ )>
3.3 g (7.7 mmol) of 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBup) synthesized in step 5, iridium chloride 1.6 g (3.7 mmol) of hydrate, 30 mL of 2-ethoxyethanol, and 10 mL of water were placed in a 100 mL round bottom flask, and the inside of the flask was purged with argon. A reaction was caused by irradiating this reaction container with microwaves (2.45 GHz 100 W) for 2 hours. After the reaction, the reaction solution was suction-filtered to obtain 2.8 g of the target yellow solid in a yield of 69%. The synthesis scheme of Step 6 is shown in the following formula (B-6).

<Step 7; Tris{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN3]phenyl-κC}iridium(III) (abbreviation: [ Synthesis of Ir(pni-diBup) ₃ ])>
Di-μ-chloro-tetrakis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN3]phenyl synthesized by the method of steps 1 to 6 -κC}diiridium(III) (abbreviation: [Ir(pni-diBup) ₂ Cl] ₂ ) 2.0 g (0.92 mmol) and 150 mL of dichloromethane were placed in a 500 mL three-necked flask and stirred under a nitrogen stream. A mixed solution of 0.72 g (2.8 mmol) of silver trifluoromethanesulfonate and 150 mL of methanol was added dropwise to this mixed solution, and the mixture was stirred in the dark for 3 days. After reacting for a predetermined time, the reaction mixture was filtered through Celite. The obtained filtrate was concentrated to obtain 2.7 g of yellow solid. 2.7 g of the obtained solid, 50 mL of ethanol, 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni) synthesized by the method of steps 1 to 5. -diBup) was placed in a 500 mL eggplant flask and heated under reflux for 20 hours under a nitrogen stream. After reacting for a predetermined time, the reaction mixture was suction-filtered to obtain a solid. The resulting solid was dissolved in dichloromethane and suction filtered through Celite/neutral silica/Celite. The obtained filtrate was concentrated to obtain a solid. The obtained solid was purified by silica gel column chromatography. Dichloromethane:hexane=1:3 was used as a developing solvent. The resulting fractions were concentrated to obtain a solid. The obtained solid was recrystallized from ethyl acetate/hexane to obtain 1.1 g of a solid in a yield of 40%. The synthesis scheme is shown in the following formula (B-7).

1.1 g of the obtained solid was purified by sublimation using the train sublimation method. Sublimation purification was performed by heating the obtained solid at 340° C. for 41 hours under conditions of a pressure of 2.6 Pa and an argon flow rate of 10.5 mL/min. After sublimation purification, 0.93 g of a yellow solid was obtained with a recovery rate of 88%.

The yellow solid obtained above was subjected to proton NMR ( ¹ H-NMR) measurement. The obtained values are shown below. Further, a ¹ H-NMR chart is shown in FIG. 47. From FIG. 47, it was found that Ir(pni-diBup) ₃ , which is an organometallic complex of one embodiment of the present invention, was obtained.

^1H -NMR. δ (CD ₂ Cl ₂ ): 0.15 (d, 9H), 0.39-0.42 (m, 18H), 0.59 (d, 9H), 1.27-1.35 (m, 3H ), 1.78-1.86 (m, 3H), 1.93-2.02 (m, 6H), 2.33 (d, 6H), 6.35-6.40 (m, 6H), 6.56-6.61 (m, 6H), 7.04-7.07 (m, 6H), 7.16 (t, 3H), 7.25 (d, 3H), 7.30 (t, 3H), 7.40 (d, 3H), 7.48 (d, 3H), 7.63 (t, 3H), 7.73 (d, 3H).

(Reference example 3)
In this reference example, a method for synthesizing Ir(pni-diBup) ₂ (mdppy), which is an example of the phosphorescent material having a five-membered ring used in Example 1, will be described.

<Step 1; Bis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN3]phenyl-κC}[2-(4-methyl- Synthesis of 5-phenyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(pni-diBup) ₂ (mdppy)])>
1.3 g (0.9 mmol) of [Ir(mdppy) ₂ Cl] ₂ and 180 mL of dichloromethane were placed in a 500 mL three-necked flask and stirred under a nitrogen stream. A mixed solution of 0.7 g (2.7 mmol) of silver trifluoromethanesulfonate and 35 mL of methanol was added dropwise to this mixed solution, and the mixture was stirred in the dark for 18 hours. After reacting for a predetermined time, the reaction mixture was filtered through Celite. The obtained filtrate was concentrated to obtain 1.9 g of a yellow solid. 1.9 g of the obtained yellow solid, 30 mL of methanol, 30 mL of ethanol, and 1.6 g (3.6 mmol) of Hpni-diBup were placed in a 300 mL eggplant flask and heated under reflux for 23 hours under a nitrogen stream. After reacting for a predetermined time, the reaction mixture was suction filtered to remove insoluble matter, and the filtrate was concentrated to obtain a solid. 60 mL of 1-butanol was added to the obtained solid, and the mixture was heated under reflux for 22 hours under a nitrogen stream. After reacting for a predetermined time, the reaction mixture was suction-filtered to obtain a solid. The obtained solid was purified by silica gel column chromatography. A mixed solvent of hexane:dichloromethane=3:1 was used as the developing solvent. The resulting fractions were concentrated to obtain a solid. The obtained solid was recrystallized from ethyl acetate/hexane to obtain 0.20 g of a yellow solid, the desired product, in a yield of 9%. The synthesis scheme is shown in the following formula (C-1).

0.19 g of the obtained solid was purified by sublimation using the train sublimation method. Sublimation purification was performed by heating the obtained solid at 320° C. for 18 hours under conditions of a pressure of 2.5 Pa and an argon flow rate of 10.3 mL/min. After sublimation purification, 0.14 g of the target yellow solid was obtained with a recovery rate of 72%.

The yellow solid obtained above was subjected to ¹ H-NMR measurement. The obtained values are shown below. Further, a ¹ H-NMR chart is shown in FIG. From FIG. 48, it was found that [Ir(pni-diBup) ₂ (mdppy)], which is an organometallic complex of one embodiment of the present invention, was obtained.

^1H -NMR. δ (CD ₂ Cl ₂ ): 0.09-0.15 (m, 9H), 0.29-0.34 (m, 9H), 0.40 (t, 1H), 0.45 (d, 3H) ), 0.51 (d, 3H), 1.18-1.24 (m, 1H), 1.34-1.49 (m, 1H), 1.70-1.78 (m, 1H), 1.88-2.09 (m, 6H), 2.17-2.25 (m, 2H), 2.51 (s, 3H), 6.30-6.40 (m, 3H), 6. 48 (t, 1H), 6.61-6.52 (m, 3H), 6.64-6.69 (m, 2H), 6.74-6.79 (m, 2H), 6.83 ( t, 1H), 6.93-7.01 (m, 3H), 7.08 (t, 1H), 7.13-7.25 (m, 8H), 7.34-7.51 (m, 6H), 7.57-7.73 (m, 4H), 7.87 (d, 1H), 7.94 (s, 1H), 8.31 (s, 1H).

(Reference example 4)
In this reference example, a method for synthesizing 2,6tBu-mmtBuDPhA2Anth, which is a fluorescent material having a protecting group used in Example 2, will be explained.

1.1 g (2.5 mmol) of 2,6-di-tert-butylanthracene, 2.3 g (5.8 mmol) of bis(3,5-tert-butylphenyl)amine, and 1.1 g (11 mmol) of sodium t-butoxide and 60 mg (0.15 mmol) of SPhos were placed in a 200 mL three-necked flask, and the inside of the flask was purged with nitrogen. After adding 25 mL of xylene to this mixture and degassing this mixture under reduced pressure, 40 mg (70 μmol) of bis(dibenzylideneacetone)palladium(0) was added to the mixture, and the mixture was heated at 150°C for 6 hours under a nitrogen stream. Stirred.

After stirring, 400 mL of toluene was added to the resulting mixture, and the mixture was suction-filtered through Florisil, Celite, and aluminum oxide to obtain a filtrate. The obtained filtrate was concentrated to obtain a brown solid.

This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=9:1) to obtain the desired yellow solid. The obtained yellow solid was recrystallized from hexane and methanol to obtain 0.45 g of the desired yellow solid in a yield of 17%. The synthesis scheme of Step 1 is shown below (D-1).

0.45 g of the obtained yellow solid was purified by sublimation using a train sublimation method. Sublimation purification was performed by heating the yellow solid at 275° C. for 15 hours under a pressure of 5.0 Pa. After sublimation purification, the target yellow solid was obtained in a yield of 0.37 g and a recovery rate of 82%.

Furthermore, the results of ¹ H-NMR measurement of the yellow solid obtained in step 1 above are shown below. Furthermore, ¹ H-NMR charts are shown in FIGS. 56A, 56B, and 57. Note that FIG. 56B is a chart showing an enlarged range of 6.5 ppm to 9.0 ppm in FIG. 56A. Further, FIG. 57 is a chart showing an expanded range of 0.5 ppm to 2.0 ppm in FIG. 56A. From this result, it was found that 2,6tBu-mmtBuDPhA2Anth was obtained.

¹ H-NMR (CDCl ₃ , 300 MHz): σ = 8.11 (d, J = 9.3 Hz, 2H), 7.92 (d, J = 1.5 Hz, 1H), 7.34 (dd, J =9.3Hz, 2.0Hz, 2H), 6.96-6.95 (m, 8H), 6.91-6.90 (m, 4H), 1.13-1.12 (m, 90H) .

100: EL layer, 101: electrode, 102: electrode, 106: light emitting unit, 108: light emitting unit, 111: hole injection layer, 112: hole transport layer, 113: electron transport layer, 114: electron injection layer, 115 : charge generation layer, 116: hole injection layer, 117: hole transport layer, 118: electron transport layer, 119: electron injection layer, 120: light emitting layer, 130: light emitting layer, 131: compound, 132: compound, 133 : compound, 134: compound, 135: compound, 150: light emitting device, 170: light emitting layer, 250: light emitting device, 301: guest material, 302: guest material, 310: luminophore, 320: protecting group, 330: host material , 601: Source side drive circuit, 602: Pixel section, 603: Gate side drive circuit, 604: Sealing substrate, 605: Seal material, 607: Space, 608: Wiring, 610: Substrate, 611: Switching TFT, 612 : Current control TFT, 613: Electrode, 614: Insulator, 616: EL layer, 617: Electrode, 618: Light emitting device, 623: N channel type TFT, 624: P channel type TFT, 900: Mobile information terminal, 901 : housing, 902: housing, 903: display section, 905: hinge section, 910: mobile information terminal, 911: housing, 912: display section, 913: operation button, 914: external connection port, 915: speaker, 916: Microphone, 917: Camera, 920: Camera, 921: Housing, 922: Display section, 923: Operation button, 924: Shutter button, 926: Lens, 1001: Substrate, 1002: Base insulating film, 1003: Gate insulation film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1024W: electrode, 1025B : lower electrode, 1025G: lower electrode, 1025R: lower electrode, 1025W: lower electrode, 1026: partition, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealing material, 1033: base material, 1034B: colored layer, 1034G: colored layer, 1034R: colored layer, 1036: overcoat layer, 1037: interlayer insulating film, 1040: pixel section, 1041: drive circuit section, 1042: peripheral section, 1044R: red pixel, 1044G: green pixel , 1044B: Blue pixel, 1044W: White pixel, 2100: Robot, 2101: Illuminance sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower camera, 2107: Obstacle sensor, 2108: Movement mechanism, 2110: Arithmetic device, 5000: Housing, 5001: Display section, 5002: Display section, 5003: Speaker, 5004: LED lamp 5006: Connection terminal, 5007: Sensor, 5008: Microphone, 5012: Support section, 5013 : earphone, 5100: cleaning robot, 5101: display, 5102: camera, 5103: brush, 5104: operation button, 5120: trash, 5140: mobile electronic device, 5150: mobile information terminal, 5151: housing, 5152: display area , 5153: Bent portion, 8501: Lighting device, 8502: Lighting device, 8503: Lighting device, 8504: Lighting device

Claims (20)

A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into luminescence, and has a luminophore and five or more protecting groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The 5 or more protecting groups are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. having either one,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. In claim 1,
Of the five or more protecting groups, at least four are each independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 12 carbon atoms. A light-emitting device, which is any one of trialkylsilyl groups. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
the second material is capable of converting singlet excitation energy into luminescence and has a luminophore and at least four protecting groups;
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The four protecting groups do not directly bond to the fused aromatic ring or the fused heteroaromatic ring,
The four protecting groups are each independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms. have one,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into light emission,
The second material has a luminophore and two or more diarylamino groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diarylamino groups,
The aryl groups in the two or more diarylamino groups each independently have at least one protecting group,
The protecting group has any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into luminescence, and has a luminophore and two or more diarylamino groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diarylamino groups,
The aryl groups in the two or more diarylamino groups each independently have at least two protecting groups,
The protecting group has any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. In claim 4 or claim 5,
A light emitting device, wherein the diarylamino group is a diphenylamino group. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into luminescence and has a luminophore and a plurality of protecting groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The protecting group has any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms,
At least one of the atoms constituting the plurality of protecting groups is located directly above one surface of the fused aromatic ring or the fused heteroaromatic ring, and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the fused aromatic ring or the fused heteroaromatic ring,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into luminescence, and has a luminophore and two or more diphenylamino groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diphenylamino groups,
The phenyl groups in the two or more diphenylamino groups each independently have a protecting group at the 3-position and the 5-position,
The protecting groups are each independently any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. has
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. In any one of claims 1 to 8,
The light emitting device, wherein the five-membered ring skeleton has any one of a pyrazole skeleton, an imidazole skeleton, and a triazole skeleton. In claim 9,
A light emitting device, wherein the nitrogen atom that does not participate in the double bond of the imidazole skeleton and the triazole skeleton has a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms. A light emitting device having a light emitting layer between a pair of electrodes,
The light emitting layer includes a first material, a second material, and a third material,
The first material is capable of converting triplet excitation energy into luminescence and has a five-membered ring skeleton,
The second material is capable of converting singlet excitation energy into luminescence, and has a luminophore and two or more protecting groups,
The luminophore is a fused aromatic ring or a fused heteroaromatic ring,
The two or more protecting groups are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. having either one,
The first material has a five-membered ring skeleton,
The five-membered ring skeleton has at least either an imidazole skeleton or a triazole skeleton,
The nitrogen atom that does not participate in the double bond of the imidazole skeleton and the triazole skeleton has a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms,
The T1 level of the first material is higher than the S1 level of the second material,
The first material and the third material are a combination that forms an exciplex. In claim 10 or claim 11,
A light emitting device, wherein the aromatic hydrocarbon group is a phenyl group. In any one of claims 1 to 12,
A light emitting device, wherein the alkyl group is a branched alkyl group. In claim 13,
The light emitting device, wherein the branched alkyl group has a quaternary carbon. In any one of claims 1 to 14,
The light emitting device, wherein the fused aromatic ring or the fused heteroaromatic ring contains any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran. In any one of claims 1 to 15,
The light emitting device, wherein the emission spectrum of the exciplex overlaps with the absorption band on the longest wavelength side of the absorption spectrum of the second material. In any one of claims 1 to 16,
The light emitting device, wherein the emission spectrum of the first material overlaps with an absorption band on the longest wavelength side of the absorption spectrum of the second material. In any one of claims 1 to 17,
A light emitting device, wherein the concentration of the second material in the light emitting layer is 2 wt% or more and 30 wt% or less. The light emitting device according to any one of claims 1 to 18,
An electronic device including at least one of a housing and a touch sensor. The light emitting device according to any one of claims 1 to 18,
A lighting device including at least one of a housing and a touch sensor.

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